One million half-price train tickets are available to buy in the first ever Great British Rail Sale.

Passengers can claim travel savings of up to 50% on rail routes across the UK - but how exactly does the deal work and where and when can you claim it?

When do the cheap train tickets go on sale?

Tickets in the Great British Rail Sale went on sale on April 19 with discounted fares available for journeys taken from today until May 27.

Why are train tickets being reduced?

Passengers can get their 'next trip at a snip' say those companies behind the promotion, which for the first time has brought together multiple train operators to offer nationwide savings.

It is hoped the sale might provide a welcome boost for UK tourism as people now ready to travel again find they can reach attractions for less by train while also encouraging more green travel across the country.

Cutting the cost of rail travel, says the government, will also 'help ease some of the pressure on family finances' at a time when the cost of living is escalating, albeit there are very few deals on offer for regular commuters or business travellers.

Transport Secretary Grant Shapps said: "For the first time ever, operators across the rail industry are coming together to help passengers facing rising costs of living by offering up to 50% off more than a million tickets on journeys across Britain.

"There’s no better time to visit friends, family or just explore our great country, so book your tickets today."

When can you travel?

There are savings to be had on a million train tickets but these apply mostly to passes bought in advance, alongside a few off peak fares. And not all routes and tickets will have a rail sale option.

The DfT explains: "Great British Rail Sale tickets are not available on all routes, are limited and subject to availability and exclusions."

Among those exclusions is that none of the half price deals available apply to travel during peak times, which has seen the offer come in for some criticism for offering no real benefits to commuters who arguably are those spending the biggest chunk of their income on essential train travel.

However among some of the biggest savings up for grabs on off-peak tickets include travel from London to Edinburgh, which was £44 and is now £22, London to Cardiff which was £47 and is now £25 and Manchester to Newcastle which was over £20 and now just £10.30.

Jacqueline Starr, CEO of the Rail Delivery Group, which is among those helping to administer the scheme, said: "We want everyone to be able to benefit from travelling by train because it’s more than just a journey, it’s a way to connect everyone to the people, places and things they love.

"As part of the Great British Rail Sale customers will enjoy over one million discounted tickets, so they can explore some of the fantastic locations that are accessible by rail."

Can Railcard discounts be applied?

Yes, it should be the case that rail operators will let you apply your Railcard discount if you own one, which could see around another 30% reduction applied to the final cost of your already heavily discounted fare.

How do I buy?

Travellers can visit the Great British Rail Sale website here to see the types of discounts on offer for particular routes and when those specific trains are running.

Tickets can also be purchased online directly from participating train operators, which are applying half price rates to a huge range of off-peak tickets sold through their websites for routes that spread the length and breadth of the country. And it is also possible to claim the discounts available when booking with a third party travel company, for example Trainline.

It is worth bearing in mind however that most of the tickets are advanced fares - which will mean you will need to commit to a particular train travelling at a specified time when you make your booking and checkout.

But the advice is to be quick - one million tickets sounds like a lot but the message from the Rail Delivery Group is that when they're gone, they're gone, so if you wish to make use of the scheme then the answer is to book as soon as possible.