Scully, who passed away last year aged 72, travelled to the festival every year, always spending at least a fortnight there, and had cheerfully promised the organisers she would "see you right when I'm gone". But they were not expecting the biggest single gift in the festival's 60-year history.

The legacy was from the sale of two homes . . . owned by Scully who was single . . . next to one another in Dublin's exclusive Leeson Park.

The money will be invested, as she intended, in a trust that will yield 225,000 a year in interest for promoting the careers of young artists.

Brian McMaster, director of the festival, which opens today, said: "This is the type of bequest arts organisations dream about. Lean's been a regular visitor to the festival for the last 10 years. She was very passionate about the arts. She left us the residue of her estate, after gifts to friends, which is two Dublin homes." He added that Scully loved coming to Edinburgh's Usher Hall to see performances. "She was very Irish. She was a lovely person but we had no idea of her wealth, she didn't flaunt it.

She had a wonderful turn of phrase. Some said she was lonely but she was a big partygoer, she loved to have a drink."

Scully was well-known on the Dublin social scene from the 1950s on. After graduating from UCC with an MA, she was heavily involved in Tuairim, the organisation set up by young people to agitate for new thinking and policies in the recession-hit Ireland of the 1950s. She then worked for the Farmers' Journal before going out on her own and establishing a PR consultancy, which proved very successful.

The former director of the Dublin Theatre Festival, Tony O Dalaigh, yesterday said the Edinburgh festival was "one of the big passions of her life", adding that she particularly loved the great orchestras."Everyone knew her there, " he said, adding that Scully had also been "a big supporter" of the Dublin Theatre Festival.

O Dalaigh said Scully was a "fantastic hostess", describing her as a "bon viveur", who loved "company, theatre and music above all".

John McMahon, a leading figure in the PR sector, said Scully was "a very intelligent lady" who was very friendly and had "a wide circle of friends and acquaintances".