Ms

Puckridge had pleaded with the Prime Minister for a face-to-face meeting when she arrives in the UK next week.

But Sir Keir has rejected her request in a “disappointing” letter.

Ms Puckridge, who served in all three branches of the Armed Forces, is making the arduous 4,400 mile journey to London from her home in Canada ahead of her centenary.

She is among almost half a million retired Britons living overseas whose state pensions do not rise with inflation.

Their weekly payments were frozen on the day they left the country, meaning many are missing out on thousands of pounds a year compared with their domestic counterparts.

The decades-long policy means they get less than half the amount of those living in this country.

Some of these pensioners live in poverty while many others are struggling to get by.

Ms Puckridge, who lived and worked in the UK until she was 76, believes she has lost out on an estimated £60,000 since moving to Canada in 2001.

In his letter the PM offered the veteran and campaigner a meeting with the Minister for Pensions, Emma Reynolds.

Expressing her sadness and disappointment at being rebuffed, Ms Puckridge said: “I am deeply saddened and disappointed that the Prime Minister feels unable to meet.

“His decision was not unexpected, but it still hurts. I do understand that he is a busy man with many pressures on his time.

But that said, I’m not making this journey and this request to meet just for myself, but on behalf of the hundreds of thousands of similarly affected UK state pensioners across the world, many of whom are much worse off than me.

“The suffering caused by this situation is real, pressing and has endured for far too long. It is for this reason that I still fully intend to travel to Westminster in a few days’ time and meet with the many political figures who have, for their part, dedicated some of their time to speak with me personally.”

Ms Puckridge added: “I do acknowledge and appreciate his offer of an alternative meeting with the Minister for Pensions.

“However, this injustice has remained unresolved for decades now. Attempts to persuade Governments of all political colours have been in vain.

“My firm view is that it will only ever be addressed by a Prime Minister who is prepared to stand up against the failings of the past and do the right thing.”

Edwina Melville-Gray, spokesperson for the End Frozen Pensions campaign, said: “We are bitterly disappointed to hear of the Prime Minister’s response coming just two days before Anne embarks on her 4,400 mile journey.

“This was an opportunity for him to set aside years of past failure on this issue and to acknowledge the toll this policy is having on so many, including Anne.

“We sincerely hope the Prime Minister will reconsider his decision not to spare of few brief moments with this inspirational and possibly unique person, who served in all three branches of the Armed Force, during the War, and whose dedication to her country has never waned”.

Labour promised to uprate pensions for British expats living overseas in its 2019 general election manifesto but didn’t include the pledge this time around.

The policy has been left unchanged by successive governments for around 70 years.

In 1955, British state pensions became payable anywhere in the world – but were not inflation-linked.

Reciprocal arrangements with only certain countries to uprate pension payments have been made in the ensuing decades.

But there are still around 150 countries where there is no agreement, including many Commonwealth nations like Canada, Australia, South Africa and New Zealand.

Campaigners argue the cost of changing the policy would be around £300 million over five years and just £50 million in the first year as it would start from the day any deal was signed, rather than being backdated.

The basic state pension is now worth £169.50 per week.

End Frozen Pensions campaigners say this means the 40% of all British pensioners living outside the UK who are hit by the policy are losing out on £3,085.16 a year if they retired in 2013 and up to £7,042.36 a year if they retired in 1983.