Like the time he stumbled on a rare fourth edition, dating from 1773, of Johnson's masterpiece, A Dictionary of the English Language.

It was 1985 and a friend rang. The owners of a rural South Australian book shop she had visited were using the two volumes (A-K and L-Z) of the precious 200-year-old work as a step.

Mr Byrne snapped it up for a bargain $350, including postage. The cover of one volume was missing, "but even in that condition, the edition was worth at least $2000 at the time".

With 10,000 items, the retired lawyer, who now lives in central Victoria, says he has one of the world's biggest private collections of "Johnsoniana", books, prints, documents and objects relating to Johnson.

He is president of the Johnson Society of Australia and a governor of Dr Johnson's House in London, where the dictionary was written.

On July 18 Mr Byrne will give a talk, called Samuel Johnson and His Dictionary, at Tonic House in Flinders Lane as part of the fourth Melbourne Rare Book Week (July 16 to 26).

Mr Byrne says Johnson was a genius for almost single-handedly compiling the dictionary, with its 42,000 definitions. Previous dictionaries were just "lists of difficult words", but Johnson illustrated their usage with quotes from Shakespeare and Chaucer.

Johnson suffered many obstacles – he had the tics and outbursts of what's now called Tourette Syndrome and had poor hearing and eyesight. He was often in debt. But he had a knack for friendship and was a gifted orator.

Mr Byrne's first Johnson purchase was in the summer of 1965-66 at an auction of the contents of an old house in Bendigo – for about $10 he bought a small, leather-bound, 1828 edition of Johnson's only novel, Rasselas.

Mr Byrne "fell in love" with the moral fable about a prince not content with his idyllic life in Abyssinia (today's Ethiopia) who sets off into the world to find happiness.

Mr Byrne now has about 300 editions of Rasselas. His latest quest is to test his theory that it has never been out of print.

He is never bored with Johnson and his milieu. "I love it. I'm obsessive about it. Apart from enjoying reading the stuff – and finding it's good fun because it's difficult, you've got to work at it and establish contacts – is the wonderful friendships and world it's opened up to me".

He is planning a trip to the Scottish islands of Skye and Iona, in the footsteps of an epic 1773 trip taken by Johnson and his friend and later biographer James Boswell. "I'll be looking for material in the little second-hand shops," Mr Byrne said. "That's where you find the treasures."