A 93-year-old is leading a campaign to change pension arrangements for people living overseas.
Anne Puckridge, a Second World War veteran, believes she has been left thousands of pounds out of pocket since moving to Canada in 2001.
She is one of around half a million Britons who have had their state pensions frozen at the level they were upon emigrating.
Pensions for those living in the UK rise every year in line with inflation.
Most of those affected live in Commonwealth countries such as Canada, Australia, New Zealand and South Africa.
Ms Puckridge handed a petition in to 10 Downing Street on Wednesday.
Ms Puckridge's pension was set at £72.50 when she emigrated to live with her daughter 17 years ago.
Had she remained in the UK, with increases she would now be entitled to £125.95 - equating to a total of £22,000 in missed pension over that period.
Ms Puckridge has described the policy of freezing pensions as "inhumane" and "illogical".
The policy does not apply to those living in the US and the EU, who see their pensions rise with inflation.
Ms Puckridge told ITV News: "When I am shopping I have to be very careful how I shop and where I shop
"I can't enjoy Christmas and birthday celebrations to the same extent because I just don't have the spare money to indulge or give to my grandchildren.
"In general it is a constant worry."
The Department for Work and Pensions said that the policy on paying uprated UK state pensions has been consistent for 70 years.
Any manual increase would cost the government £500 million a year, according to the DWP.