Eric Clapton would have been a bricklayer if he didn't become a rock legend.

The 'Tears in Heaven' hitmaker got the chance to try his hand at the labouring job when he worked briefly with his grandfather as a youngster, and says his work ethic and ''master'' craftsmanship rubbed off on him.

Asked by Jools Holland at the UK premiere of his new movie 'Eric Clapton: Life in 12 Bar Blues' what he'd have done instead of music - he said: ''Bricklayer or plasterer. For a little while I worked for my grandfather. And he was very strict and very noble.

''He never took a raise. He worked for the same amount of money all his life.

''And he was a master craftsman. And that was very important for me to observe.

''That I could take that ethic anywhere.

''He worked me very hard. So, I always thought, Well, if music doesn't work ... 'Cause I had the time of my life on that building site.''

The 72-year-old music legend teamed up with filmmaker and long-time friend Lili Fini Zanuck for new movie 'Eric Clapton: Life In 12 Bar Blues', which documents the rocker's spiralling addiction to drugs and alcohol, finding out the woman he believed was his mother was actually his sister, being rejected by his real parent, and the tragic loss of his four-year-old son Connor, who fell to his death after falling out of a window in a New York City apartment.

A continuous theme to the 'Layla' hitmaker's personality, which director Zanuck chose to pinpoint, was how Clapton would just start getting onto a good thing with each of his groups, including The Yardbirds, Cream and Derek And The Dominos, and then he'd move on to the next thing.

The 'Layla' songwriter - who has a net worth of around $250 million - also admitted to never being concerned with how much he'd earned or spent over the years, despite the movie showing a young Clapton making his first ever purchase, his impressive Hurtwood Edge mansion in Surrey, England.

He explained: ''About the time [Derek And] The Dominos broke up [1971]. That thing of calling my band The Dominos was me trying to back out of everything. I still don't know how much money I've got or how much I've spent. I deliberately avoid knowing, because I'm a working class boy. It seemed like my life, from the minute I started to listen to blues music ... it was all about obscurity and mythology. I sabotaged everything I got involved with that started to look like it was going to be a success.''