Update: 12.01pm, Sun 1 April: Since we first published this story, a rail industry spokesperson's been in touch with the following statement: "Check the date. Train companies would NEVER make passengers who pay £1,000s a year stand all the way to work and all the way home."

Commuters across the UK will be able to slash the cost of getting to work each day by buying a new kind of discounted season ticket, but there's a catch - you're not allowed to take a seat, even if there's one available.

The new 'Happy Stander' fare has been announced by rail firms in a bold bid to make seating an optional, and chargeable, extra.

Tickets were supposed to go on sale today, but have now been delayed until later this month. Passengers who buy the discounted tickets are expected to be able to save at least 14% on the usual price, which could equate to £100s saved each year on some routes.

And while the price cut will be a welcome relief for many, 'Happy Stander' passengers could face an on-the-spot fine if they tire and are caught sitting - so the potential savings rest on your levels of endurance.

How the new season tickets work - the full ups and downs explained

If you buy a 'Happy Stander' fare, your normal season ticket will be stamped with a special logo, which rail firms say should be "instantly recognisable" to ticket inspectors as it will have distinct lines covered in leaves.

Passengers with the ticket will only be allowed to stand for the entire duration of their journey, even if a seat is available. If you are caught sitting, you can be issued with an instant fine of up to £20 and required to purchase a full 'premium' ticket with a seat included.

However those who do cough up extra for a 'sitting' ticket still aren't guaranteed a seat, and WON'T be able to apply for the standing-only discount if they get on the train to discover no seats are available.

Rail bosses are understood to be concerned about the potential for passengers to abuse the new discount, and strict rules on leaning, perching and hanging on have been drawn up.

Standing passengers will be permitted to hold onto railings and other passengers, but balancing on luggage racks is strictly forbidden. Those who lean at an angle of more than 60 degrees could be fined on a 'three leans and you're out' basis.

Rail shake-up 'inspired by budget airlines'

A rail industry spokesperson said: "We have spent a lot of time listening to customers in developing these plans - after all, cost and the lack of seats are two of the biggest complaints we get.

"We believe the introduction of the new 'Happy Stander' fare addresses these concerns. It aims to make those standing feel good about it, plus gives passengers the chance to stretch their legs and enjoy the substantial health benefits of not sitting.

"This revolutionary new pricing structure is inspired by the pioneering example of budget airlines in stripping back services to cut costs - and a 'standing only' season ticket is just the start. We're also looking at redesigning trains and stripping out seats from some carriages to allow more passengers to benefit from the standing-only discount and free up space for other premium services such as toilets."

MoneySavingExpert got to try out the new system on a two-hour standing-only press trip from London Kings Cross to Polarfoil - but sadly ended up being issued with a fine.

MSE travel editor Eileen Dover said: "We need to see prices first before we can say if this is truly MoneySaving or not, but the implementation also has to be right - the paying passenger can't be taken for a fool."