The multi-millionaire philanthropist Lord Hamlyn, who blew open the genteel world of publishing by selling mass market books at bargain prices, has died aged 75, his family revealed yesterday.

Despite avoiding publicity, he was one of Labour's most high-profile donors and was named as the man behind a £2m mystery donation to the party declared last Christmas.

Lord Hamlyn died at the Royal Marsden hospital in London on Friday with his wife, Lady Helen, and children Michael and Jane at his bedside. He had been fighting cancer and also had Parkinson's disease.

Last night friends praised his courage and humour in illness, and his lifelong determination to help others.

The son of a Jewish paediatrician who left Germany in 1933, he came to Britain as a child, anglicising his name from Paul Hamburger to escape taunts of "sausage".

Leaving school at 15, he began his career selling second-hand books from a market stall, before going into publishing and building up a fortune reckoned at £370m.

Lord Hamlyn broke the mould by selling mass market books cheaply and seeking out unconventional outlets such as supermarkets.

He founded the Paul Hamlyn Foundation, which donates to the arts, and has funded the Paul Hamlyn Library at the British Museum and the Hamlyn Week at the Royal Opera House, which provides cheap tickets to give a wider audience access to performances.

"The main theme of his life was that he wanted to give people wider access," said the Labour peer Lord Gavron, a friend since the early 1960s. "He felt it was unfair that some of the better things in life were only available to the privileged."

Lord Owen, another friend, said Lord Hamlyn's philanthropy was shaped by his wartime experience as a Bevin boy in the collieries of south Wales.

"I think he was a very committed supporter of the under-dog. He always championed those who were less well-off, who had less opportunity, particularly in the arts.

"It all stemmed from his early years, coming from Germany, and being a Bevin boy. He never seemed to forget that he had a lot of money and could use it to help others."