The Onegin filmmaker, who is siblings with actors Ralph and Joseph, is preparing to walk down the aisle for the first time with Detmar, a lawyer and art dealer, who was married to Isabella from 1989 until her death in 2007.

"Detmar and I are engaged, I am so happy," she tells Britain's Daily Mail newspaper. "My ring is being made as we speak... It’s a really unbelievable diamond ring with a Mogul emerald. It’s like a spaceship...

"He’s very eccentric, full of feeling, he’s completely out there, but also he’s an absolute gent... I feel very blessed."

The 52 year old was in a relationship with filmmaker George Tiffin for more than 20 years but he was against the idea of marriage. They split in 2011 and have three children Titan, Hero and Mercy. Hero starred in Harry Potter and the Half-Blood Prince as a young version of Ralph's character Lord Voldemort.

Martha was also engaged to hedge fund tycoon Issam Kabbani in 2011, but their relationship faltered.

Isabella Blow was famous for discovering model Sophie Dahl and fashion designer Alexander MCQueen. She committed suicide in 2007.

Detmar then married Brazilian artist Mara Castilho and they had a son named Sasha, but she left him in 2011.