Sir Alec Guinness wasn't a big fan of fellow actor Sir Lawrence Olivier.

The late British actor branded Sir Lawrence a ''tiresome'' performer and was less than impressed by his historic performance in 'Oedipus Rex', previously unseen diaries have revealed.

Writing in his diary the day after Lord Olivier's death, on 12 July 1989, he explained: ''His 'I defy you, stars' in 'Romeo' was memorable. And so was his Poor naked wretches etc in 'Lear'. But his famous howl in 'Oedipus' I thought just tiresome.

''He knew every trick of the trade and used every one, including, when he made his first entrance the lights coming up a few points and going down again when he left.

''He was always very conscious of the audience - and his own powers over them. I'm not sure he was an artist but he was total actor - a giant among actors.''

The British Library have just acquired the personal archive - which includes 900 letters to loved ones - from Sir Alex's family for a reported £320,000. It dates from the 1930s until his death in 2000 aged 86.

Sir Alec is best known for his 1957 Oscar-winning role as the commanding officer in 'The Bridge on the River Kwai' and playing Jedi master Obi-Wan Kenobi in the 'Star Wars' films.