The Georgian vicar whose ideas could have saved Thameslink passengers from misery

London Blackfriars: not a Thameslink train in sight. Image: Getty.

The Reverend Thomas Bayes was born in Hemel Hempstead, Hertfordshire, in 1701. He grew up in London’s Southwark, and died in Tunbridge Wells, Kent in 1761. Had he lived 300 years later, a railway running from Hertfordshire to Kent via London Bridge would have been rather useful to him. And if the people who currently run that railway had paid more attention to him, everyone on the route would be a lot happier.

The Thameslink service links commuter towns to the north and south of London via the city centre. After a major timetable change this May, the network descended into chaos. Instead of the intended massive increase in services, the service through London collapsed.

Things got so bad that Govia Thameslink Railway (GTR) had to hire extra security staff to defend train crew from angry passengers. GTR’s CEO announced his resignation, although he’ll stay in place until the company finds someone willing to take on the poisoned chalice.

So what happened? First, some background. In the 1980s, British Rail (BR) reopened a disused freight line across London. This allowed BR to shift commuter services away from terminal stations, and free up peak hour space at St Pancras and Blackfriars.

This scheme worked so well that the railway went for a second round. This programme was called Thameslink 2000, after the year it was supposed to be finished. It’s nearly finished now (that’s another story). The timetable change was supposed to benefit from the new infrastructure.


Instead it collapsed. London Reconnections has outlined the underlying issues: in short, new trains were delivered late, so drivers didn’t know how to drive them; when GTR took over the franchise in 2014 the previous operator hadn’t been training new drivers, so it’s been playing catch-up; GTR’s training programme relies on drivers working overtime, which many of them don’t want to do; some new tunnels didn’t get handed over until far too late; and GTR didn’t transfer drivers to new depots in time. This meant that many drivers weren’t qualified to drive the new trains along the new routes in time for the change.

Some people might have decided to cancel at this point. But GTR had a cunning plan.

For a train to carry passengers, it needs to have a driver qualified to drive the route that it’s on, a driver qualified to drive the train, and a driver qualified to carry passengers. These don’t have to be the same person, so if you must, you can have three people in the cab, one of whom is qualified to do each. This isn’t ideal; but it’s safe, and it works.

GTR worked out that – between the drivers it had who were trained on the new trains, the drivers it had who were trained on the new routes, and the not-passenger-qualified drivers who had tested the new trains before they entered passenger service – it had enough drivers to run the new timetable by doubling or tripling up in the cab.

But it didn’t. Which is where the Reverend Bayes comes in.

The Reverend Thomas Bayes. Image: Wikimedia Commons.

If you’re working out the number of drivers you need based on traditional probabilities (statisticians call this ‘frequentism’), you look at five factors: the total number of trains needed, the number of drivers qualified for each part of the route, the numbers qualified for the right trains, the number qualified to carry passengers, and sickness/absenteeism rates.

Then you can work out the number of trains to run, based on the number of people likely to be around and qualified. On the evidence we’ve seen so far, GTR appear to have done this, and found that they were, narrowly, capable of running the service.

But there’s a problem here: people don’t come in percentages. Either you have a whole train driver or no train driver at all. And if you don’t have a train driver qualified to drive the train to Finsbury Park when it arrives at London Bridge at 7:30am on a Monday, then your whole timetable is stuffed.

Agent-based modelling is a more complicated way of looking at things than simple probability. But it has a huge advantage over simple statistical models, which is that it can deal with lumpy problems like train drivers. It requires a lot of hard maths, of the sort pioneered by the Reverend Bayes.

You use this maths to set up simulations of what will happen if you try and run the trains you have on the routes you have, using the drivers who you have. So your computer becomes a gigantic nerdy train simulator game, running the entire train timetable thousands of times, and seeing what happens each time you try to run it.

The conditions are slightly different each time: on run 3, the driver who’s off sick is Alan from Luton who is qualified to drive to Brighton but not Maidstone; on run 15, it’s Barbara from Brighton, who is qualified to drive to London Bridge but not Cambridge. The closer you can match the simulated agents to your real roster, the more accurate the simulation is.


Using this model, GTR would have found that having the right number of qualified crew is no use in itself: one person in the wrong place at the wrong time can make the whole thing fall over, even if there’s another qualified person on shift, because that qualified person is an hour’s cab ride away.

Because they didn’t do this kind of modelling, they took false reassurance from their data showing that they had enough crew. The first time their assumptions were put to the test was the first day of the real timetable – when it all fell to pieces.

If GTR had used agent-based modelling to test the new timetable, they would have had to ditch it at the last minute, which would have been horribly embarrassing. Maybe that’s why they didn’t do it. But looking back, it would have been much less embarrassing than what actually happened.

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The media scumbag’s route of choice: A personal history of London’s C2 bus

A C2 bus at Parliament Hill. Image: David Howard/Wikimedia Commons.

London’s C2 bus route, which runs from Parliament Hill, by Hampstead Heath, down to Conduit Street, just off Regent Street, is one of the bus routes recently earmarked for the chop. It has oft been noted that, of all the routes recently pencilled in for cancellation after a consultation late last year, it was the one most likely to survive, for the simple reason that it links liberal suburban north London with BBC Broadcasting House and Soho; it’s thus the route most likely to be used by people who can convince someone to let them report on its imminent demise.

So it would come as no surprise that former Guardian editor Alan Rusbridger took to the Camden New Journal when the consultation began, arguing that it would be a disservice to the local community to discontinue a route where you can always get a seat – seemingly missing the point that the fact you can always get a seat is not a great sign of the route’s usefulness.

It wasn’t always that way. When I left university in 2000, and moved from accommodation near college to up to a rented shared house in N6, the C2 was my bus. I commuted to Soho for sixteen years: for more than a decade from flats around the Swain’s Lane roundabout, and for five years from Kentish Town. While my place of work bounced around from Golden Square to Lexington Street to Great Marlborough, it was always the most convenient way to get to, and from, work; especially given the difference between bus and tube prices.

So when it comes to the C2 I’ve seen it, I’ve done it, and bought the bus pass. And by bus pass, I mean those little paper ones that still existed at the beginning of this century. Not just before contactless, but before Oyster cards.

More importantly, it was before London buses operated a single zone. There was an outer zone, and an inner zone, with different prices. To travel from one zone to another cost £1.30, meaning an all cash commute was £2.60, whereas a paper bus pass was £2.00. That made it worth your while to divert to an early opening newsagents on your way to the bus stop (GK, in my case), even if you only got two buses a day.

It’s a measure of how greatly London’s buses have improved over the last twenty years, since first brought under control of the mayoralty, that pretty much everything about this anecdotage, including the prices, seems faintly mad. But there’s more: back when I started getting that bus down to Stop N, literally at the very end of the route, the C2 used single decker buses with a single door. It’s an appalling design for use in a crowded city, which meant most of any journey was, for most passengers, spent fighting your way up and down the middle of the bus to find a seat, and then back again to get off; or – and this was more likely – fighting your way up the bus to get into standing space the driver insisted was there, before fighting your way, etc.

Such buses – and in my former life in the English Midlands I went to school on one of these buses every day – are perfectly functional where bus stops are infrequent and buses rarely standing room only. But running through Camden Town at rush hour, they’re wholly unfit for purpose.

A Citypacer. Image: RXUYDC/Wikimedia Commons.

It could have been worse. I didn’t know this at the time, but a few years before the C2 route had been run using Optare City Pacers. Those are, let us be frank, not really buses at all, but minibuses. That’s something the reveals the C2’s origins, as a hopper route to the west end largely intended for the daytime use of Gospel Oak’s pensioners in the years immediately before bus privatisation. (The C11 has a similar origin, taking the same constituency from Archway to England’s Lane.)

Once responsibility for London Buses was moved to the newly established mayoralty, things improved dramatically. Under Ken Livingstone it went double decker in 2005, and 24 hour in 2007. Under Boris Johnson it was extended from its once, and future, terminus of Conduit Street to Victoria Station, swallowing up the cancelled sections of the 8 bus; this extension was quietly disposed of a few years later, once it was clear no one would notice. (I did.)


In those years I must have taken a C2 the best part of ten thousand times; but for all the years when I wouldn’t have been able to live without the C2, times have reduced its utility, and not just for me. I’m now a 214 sort of guy: these days the top chunk of the C2 route is duplicated exactly by that other bus, which starts up in Highgate Village and, once it gets to Swain’s Lane, follows the same path until the fork of Kentish Town Road and Royal College Street, opposite the long defunct South Kentish Town tube station.

From a few hundred metres below that point, at Camden Gardens, stop C, the 88 starts. That duplicates the rest of the C2’s route, with the exception of the run down Albany Street and onto Great Portland, for much of which the C2 is the only bus.

So the C2, old friend that it is, is pretty redundant in the age of the hopper fare, which allows you to change buses without paying a second fare. That’s even more true now the C2’s otherwise un-serviced stops are being giving over to a re-routed 88, which will pick up the C2’s most northern leg, by not finishing at Camden Gardens anymore and instead going all the way to Parliament Hill Fields. Which will be nice for it.

All this, however, ignores the best reason for getting rid of the C2 (or rather for merging it with the 88, which is what’s actually happening): that first character. The letter. Who wants a bus route with a letter in front of it when even half the night buses don’t have the N anymore? It’s relic of the route’s aforementioned origins as a ‘Camdenhopper’.

That C is twenty five years past its own utility. It’s just untidy. City Metric hates that sort of thing. Get rid.