Their friendship spans seven decades, 3,500 miles and is based on hundreds of handwritten letters.

Back in the 1940s, two 10-year-old girls started exchanging tales about school, their siblings and their hobbies.

And next weekend, penpals Muriel Cowley and Peggy Shafer will celebrate their friendship with a reunion in Norfolk.

Mrs Shafer, who lives close to Philadelphia with her husband, Dave, penned her first letter to Muriel Cowley from Attleborough on August 22, 1944.

Mrs Cowley said: 'My neighbour was in the army and he was posted to America to help build defences against the Japanese. He got to know the people out there and one of the men had a teenage daughter, Hazel, and she asked my neighbour if he could find a penfriend.

'He wrote to his wife and she suggested my sister as they were closer in age. But Hazel had a friend, Peggy, and she wanted to write, too.

'When I was 10 years old, I had a great family life. My father was in charge of refuelling the flying boats and it was a top priority job and I was very lucky that I didn't have someone in active service.

'Peggy and I wrote about school. I just used to love writing. We couldn't do much in those days because of the blackouts.'

Mrs Cowley also wrote about the sweet ration and how pleased she was that it was being introduced as it meant everyone was able to have some.

They soon found out that they had a lot in common and formed a strong friendship.

'We were both born in the same month of the same year. We had the same initials – Muriel Herman and Margaret Hicks – and we both had a brother and a sister.

'We both married naval personnel whose fathers had both died when they were tiny and were brought up by stepdads.'

They married a year and a day apart and their daughters were born within months of each other, followed by their sons.

Unbeknown to each other, they also booked a cruise to the Fjords to celebrate their 80th birthdays in September.

Mrs Cowley, who moved to Norfolk from Dorset in 1995, said: 'In the 40s it took time for things to get over to the States. It wouldn't have been taken over by aircraft, it was by boat.

'I remember the first present she sent me – it was a bandana. I loved it and I wore it everywhere.'

The pair first met in 1974 when Mrs Cowley flew to America.

'It was incredible,' she said.

'She carried a rose for recognition but she didn't need it. It was like meeting family, we were made to feel so welcome.

'I had to make a little dictionary for myself for the different words. A faucet is a tap, drapes are blinds and a trunk is the boot of a car.'

The last time they met was on a shopping trip to New York in 2004.

The friends have supported each other through difficult times, including the loss of Mrs Cowley's son, Robert, who passed away four years ago. She is my oldest friend and we have grown up together. We are still very close,' Mrs Cowley added.

And the grandmothers have both embraced the digital age and now they email each other.

To celebrate their years of friendship, Mrs Shafer and her husband are visiting Mrs Cowley for high tea, which is being organised by Mrs Cowley's daughter, Elizabeth Cowley-Gwilliams.

They will enjoy champagne, cakes and sandwiches in Ms Cowley-Gwilliams's garden in Banham.

Some of their early letters and photos will be on display for family and friends to see.