Horrified Ben, 72, said yesterday: "How could I have been such an idiot?"

Lowry gave Ben the ten sketches in the 1950s when he was his milkman.

Back then the Manchester-born painter was still making a name for himself.

Grandad Ben, then a teen, threw away the drawings because he did not think they were any good.

Experts reckon they would now be worth a seven-figure sum. Ben admitted his blunder at the unveiling of a Lowry-style mural in Mottram, Cheshire - his home town where Lowry lived from 1948 to his death, at 88, in 1976.

The tribute to the now world-famous artist features villagers he knew, including Ben delivering milk. He said: "I knew Lowry was an artist, but nobody thought he was anything special. A lot like me thought they could do better.

"He started giving me sketches when I was delivering. He said I could throw them away if I didn't want them. I just thought they were little sketches anybody could do.

"I'm not a big art lover and it only dawned on me they might be valuable when Lowry's name started to get out."

Ben's wife Beryl said: "It's a shame, but money isn't everything."