A veteran of Britain’s atomic testing programme has spoken of his joy after Boris Johnson announced a commemoration day and called for medals to be awarded.

The outgoing Prime Minister announced he will commission an oral history to memorialise the service of veterans who suffered debilitating health problems, while the country will commemorate the 70th anniversary of the first UK nuclear test.

In a letter published on Twitter moments before Lis Truss was named his successor, Mr Johnson urged the next government to consider a medal for nuclear test veterans.

Mr Johnson, who was the first prime minister to meet a group of veterans and campaigners in June, wrote: “I was privileged to be the first Prime Minister to meet some of you in person.

“Hearing your accounts first hand, I’m determined that your achievements will never be forgotten.

“So I am commissioning an oral history to memorialise your service and later this year we will mark the 70th anniversary of the first UK nuclear test.

He added: “The Government will provide funds for other schemes to remember your contribution to national security and offer support as necessary.

“And I have asked that we look again at the case for medallic recognition, because it is my firm belief that you all deserve such an honour, and this work is now in train.”

Eric Barton, an 80-year-old veteran stationed on Christmas Island, said: “It’s been a long time coming. We’ve been fighting for this since 2008, but people have been fighting for years before that.

“It brings me joy to finally have recognition. The MoD (Ministry of Defence) for years have just been saying that there was no danger, no error, no risk in it.

“Now with freedom of information, all these documents are coming out to prove them wrong.”

Mr Barton was stationed on Christmas Island during Operation Dominic, a series of 31 nuclear test explosions conducted in 1962 by the United States in the Pacific.

The operation saw 24 bombs set off in 78 days.

Labour MP Rebecca Long-Bailey, who previously asked Mr Johnson to meet the group of British nuclear test veterans and their families, urged Ms Truss to recognise their “pain and suffering”.

In the June meeting, campaigners gave Mr Johnson an October deadline to resolve the issue and requested a medal to mark the ‘Plutonium Jubilee’ – 70 years since the first British nuclear test in October 1952.

Alan Owen, a descendant of a nuclear veteran and founder of Labrats, which represents veterans and their families, said: “It was great to hear from Boris Johnson on his final day and for him to provide us with a commemoration day later on in October for the 70th anniversary.

“It was extremely good to hear that he firmly believes that the nuclear veterans deserve a medal and that he’s put in place the train of action to ensure that it happens.

“I think for a prime minister to say that it’s their firm belief that we all deserve such an honour is fantastic. It’s what we were looking for. It doesn’t go as far to say you’ve got your medal.

“And until that happens, we will always be waiting, but it’s great to have this recognition from Boris as he leaves.”

Ms Long-Bailey said: “It is positive that as a last act of office Boris Johnson has chosen to write to nuclear testing veterans highlighting his support and the action he has taken so far to meet the promises he made to them.

“It is now incumbent on the new PM to recognise the pain and suffering these veterans and their families have been through and urgently ensure that calls for medallic recognition, support and research are met.

“These men gave their all to protect us. It is high time we honoured and supported these veterans and their families like other countries have already done.”

Approximately 20,000 British soldiers, mostly conscripts, witnessed hundreds of atomic tests and were exposed to radiation.

The most notorious was the Operation Grapple Y in 1958, which was over 100 times more powerful than the bombs that levelled Hiroshima and Nagasaki.

There are an estimated 1,500 surviving ex-servicemen of the experiments.