Johnny Waldron knocked him out twice in the first round. This is a guy who lost his Pro licence because he had an eye injury! Cliff Fields knocked him out in the first round as well, and he was an average pro boxer who could be classed as a journeyman at best. Rumour has it Lenny was out cold for over 2 minutes after one of his losses
Saying that, it has been backed up by loads of witnesses that Lenny was noce confronted by 18 men in a pub one afternoon and he knocked the shit out of all of them. In regards to unlicensed boxing, i dont really know. Roy Shaw was as good as they got, as was Bartley Gorman (although Gorman was a Gypsy Boxing champ and was KOTG for 20 years). If you wanna talk about street fighting, then Lenny is right up there, probably the best.