Help needed - basic criminal records check - job application

Any of you friendly folk know much about the above?

I've been offered a new job (working for an insurance company) who have made me an offer subject to references and a basic criminal record check...

So, I have a caution for possession of a class b drug in the last few years. Will this show up on basic checks bearing in mind it's only a warning and not a conviction?

Any help would be appreciated.