Exhibition of letters reveals stories of love, loyalty and devotion

It was a love letter written by one of the more important British spies of the cold war that made Tom Brass realise he had never fully known his mother.

- Amelia Hill

The spy in question was John Cairncross, the alleged fifth man in the Cambridge spy ring, whose spycraft helped the Soviets win the Battle of Kursk and turn the tide of the second world war.

"My mother came from a category of women whose lives were deemed to be of little or no interest," said Brass. "But these love letters - which she tucked away in her copy of Cairncross's autobiography - show that before she was a wife and mother, she was loved by a spy for her vibrancy and intelligence."

Cairncross was known to be prickly and resentful, but the previously unseen letters to Gloria Barraclough - his "Dearest Gloria" - show him to be fond and elegant. "Writing to you seems to have some magical effect on me," he wrote in 1944, at the same time as he was working under Kim Philby in MI6's counterintelligence section. "Your letters have a lightness, vivacity and joie de vivre ... a fresh voice from an exquisite past."