There are many things I’ve learnt to distrust over the years. PRs who start a conversation with the phrase “have you got 30 seconds?”, my Dad’s woefully optimistic assessment of the carnage he’s unleashed on his PC, and West Ham’s back four, for instance. But none more so than the battery indicator on mobile phones.

They are pathological liars. They’ll spend two days displaying five full bars of battery goodness, only to chomp their way through the remaining bars in six-and-a-half minutes. I’ll never buy a Sony Ericsson phone again after the time I left the house with the full five bars of battery, only to end up on the motorway hard shoulder a couple of hours later, barking instructions to my girlfriend in a demented verbal shorthand, because the battery had inexplicably drained down to the last sodding bar.

And what does the phone do when it’s approaching battery Armageddon? Does it go into Apollo 13 mode and start shutting down every last unnecessary amp of power? No, it starts twittering out “battery low” warnings like a budgie on Speed, serving only to chip another few seconds off your remaining talktime in the process.

That is until the Nokia E71 arrived. You may be aware of others, but this is genuinely the first phone I’ve ever owned where the battery indicator actually indicates how much battery life is left. This became gloriously apparent on Friday night, when my train decided to take an unscheduled stop somewhere between Three Bridges and Haywards Heath. For an hour-and-a-chuffing-half.

The train driver is probably right now being head-hunted by the SAS, because if this chap was dropped behind enemy lines and taken prisoner, there’s no amount of nipple-tweaking torture that could persuade him to start talking. Thus, I headed over to the BBC Travel website to find out what the problem was, and then sent a succession of SMS progress reports to my girlfriend, all with my battery indicator dangling on a single precarious bar.

I even managed to fire up the GPS and find out exactly where I was marooned, and read a few angry comments on Twitter from fellow commuters. Indeed, the phone was still perky when I arrived home some three hours later.

So battery indiciators have stopped lying to us. Perhaps, Microsoft can headhunt the person responsible and set them to work on Windows’ progress bars?