It not quite as simple as that.
There are three types of CRB check
Basic - Spent Conviction not declared
Standard - All convictions declared
Enhanced - All Convictions AND anything 'in-process' at the courts
Its a matter of discretion by companies what level of disclosure they use and what they regard as a no-no
I'd ask for an enhanced and you will get whats on the system
for you - You can check if its correct and it will facilitate any discussion as to what's OK by the emplyers and what's not
Sadly, however as IMCRenewal says, a conviction of any type will not help you in a competitive market..
More info at
http://www.crb.gov.uk/