So, how late was your train? The 07.29 Brighton to London Victoria service has made headlines as the worst in Britain, after failing to roll in at its scheduled time of 8.35am on a single occasion last year. It may be little consolation to those trundling slowly through Sussex to know their train may not be the absolute worst: neither Network Rail, the Department for Transport or the rail regulator have those figures to hand. It was left to angry commuters to ask train operator Southern to research and confirm the anecdotal suspicion that this particular service never actually ran to schedule, which, to their credit, they did.

According to the official standard, though, the 07.29 slowcoach was only late 73% of the time. That is because punctuality, for commuter services, is officially defined as up to 4 minutes and 59 seconds behind time. On long distance services, there’s an extra five minutes leeway. Compensation is normally only paid for delays six times the lateness threshold, at a minimum of 20% of the fare for an hour’s delay, though you get 50% back for 30-minute wait on Southern.

Several commuters on the 07.29 confirm that the headlines came as no surprise. Rebecca Francis, 37, said she failed to reach work in Marylebone on time for the past three months: “It’s at least 10 minutes late on a daily basis. Between October and December last year, I had to apply for delay compensation at least five times for this train.” Southern’s stats show the train gets in less than 10 minutes late most of the time – 71% of trains last year – so only a small part of the annual season ticket cost (now more than £4,000 since the January fare rise) can be clawed back.

Southern thinks, but can’t confirm, that the 07.29 is the only one of its services never to arrive to the minute. The following and preceding Brighton-Victoria trains actually did meet their schedule on occasion, albeit on only 1% and 2% of their attempts – although the poor 07.44 presumably stood little chance of overtaking its predecessor. Southern admits the stats are “not brilliant” but says the line is one of the most congested routes in the country and the knock-on effects of delays can be enormous. A 30-point improvement plan has been unveiled. “Providing a punctual, reliable service is one of our top priorities,” it pleads.

In railways as in physics, the elasticity of time is a hot topic. Two years ago, then transport minister Norman Baker infuriated some train operators by trying to make the so-called “right-time” – punctuality as it appears on commuters’ watches, expectations and real-life plans – the default measure of lateness, rather than the 5- or 10-minute relaxed “public performance measure”, the yardstick on which reputation and commercial franchises are judged. At time of writing, a mere 44% of Southern trains between Victoria and Brighton had run late on Tuesday by the official count. The truth can only make us angrier.