^^ Does the Rehabilitation of Offenders Act apply in this instance...?
At any rate, if the OP goes through the correct channels by applying for a visa and filling in the criminal record section correctly, I'd say there's (next to) no chance of a visa being granted.
Similar questions to this have been posted many times in here, and some people have suggested lying on the ESTA application form because the US authorities have no means of accessing the UK's PNC... I'm pretty sure that in itself would constitute a crime so would be foolish in the extreme, especially with an existing criminal record...