Seatfrog: The app which allows you to bid for an upgrade on Virgin Trains East Coast line

Perhaps you have seen the entertaining new Emirates ad, urging travellers to “upgrade your airline”?

A good way to do just that: switch from an airline that squeezes in 10 economy seats abreast on a Boeing 777, eg Emirates, to one that fits only nine – such as British Airways, at least from Heathrow.

There is one sure-fire way to travel first class: buy a first class ticket. The trouble is, they cost far more than economy seats, and don’t get you there any faster.

As with planes, so with trains. Occasionally you can bag a bargain advance first class ticket for little more than standard price. But most of the time you can’t. When I found a rail fare from York to London King’s Cross of just £11 (booking many weeks in advance), first class was several times more expensive.

So when I stepped aboard the 2.02pm at York station, it was a treat to be in the posh seats. I had successfully used a new app called Seatfrog, which offers “targeted upsell opportunities” in the travel industry jargon – also known as on-the-day train upgrades.

You are probably familiar with Weekend First, which entices standard passengers into seats on Saturdays and Sundays which would otherwise go empty in return for £10-£25, depending on the length of the journey. But Seatfrog works from Monday to Friday, which is when you really want to be in first class because lots of other stuff is included.

Here’s how it works. Start with an advance ticket in standard class – at present only on Virgin Trains East Coast, though other operators are watching. Download the Seatfrog app. Tap the train booking reference into the app, along with your credit card details; Seatfrog promises, “You only pay if you win”.

If your train has Seatfrog space, two and a half hours before departure you are invited to participate in an online auction.

The minimum is £5, but to try to avoid having to immediately up the bid I started at £7. Initially I seemed to be in the lead, but then I was nudged down the pecking order by an unseen rival. So £9, then £11, where I stopped because the notion of paying more for an upgrade than I had for the original ticket did not appeal. Half an hour before departure I was told I had “won”.

First class passengers aren’t like the rest of us. They enjoy more space than a prebooked Thomas Cook sunlounger, and seats that actually line up with windows. They have no need to type implausibly long codes or their credit-card details to get wi-fi on trains; it just flows mellifluously through the first class salon, if I might call it that. They don’t queue up at the buffet to pay inflated prices, because the buffet comes to them. And it’s free.

Juliana was dispensing hot meals even in mid-afternoon; the beef rendang was compact but tasty, and you can fill up with fruit or biscuits as you please. Complimentary drinks, too, anywhere on the water-to-wine spectrum. Half an hour into the journey I felt so calm and relaxed (a new sensation for me, at Doncaster station at least), that I went the whole wellness/yoga/mind/body/spirit distance and asked for a green tea. Juliana disappeared to fetch a bigger mug, saying that the brew was better served in a larger vessel.

One aspect that wasn’t brilliant: the 2.02pm was downgraded, chronologically speaking: while our train was ready to go on time, it was held up for a late-running express from Edinburgh, and as a result we got stuck behind a succession of slower services. But if you’re going to be delayed, better that it happens in a spacious salon awash with green tea.

What haunts any blind bidding transaction is that you could have got the same thing for less. Talking to other Seatfrog users, it seems I may have overbid: on middle-of-the-day trains some claim to have won an upgrade for as little as £7 or £8. But I underbid relative to the benefits of first class.

Don’t expect a bargain on a Monday morning or Friday evening train from Newcastle to London. But you might want to try Seatfrog sooner rather than later, just in case it becomes too successful and causes “cannibalisation” – not adding human flesh to the buffet choices, but tempting passengers who would normally buy first class to take a chance on bidding instead, reducing revenue.

Meanwhile Seatfrog may soon take off for flight upgrades. Iain Griffin, the chief executive, told me: “We’re working with a bunch of airline partners at the moment.” I wonder if they include Emirates?