I have never heared of anyone being Prosecuted for using a company name under a sole trader, even the banks open business accounts for us under your business names, but add trading as,
but in reality, you are only allowed to trade useing your own name as a sole trader, ie A.Smith, window cleaners, or A.Smith & son's window cleaners. etc. but like I have said I have not heared of anyone being prosecuted for it, and hundreds of us do it.