I can't speak for the UK, but I know when filling out job apps in the US there is a section about criminal disclosure. There is usually a line that says to omit traffic violations i.e., parking tickets etc but it still seems to confuse people and they put it down when they don't need to and then it gives the HR people a second glance and raised eyebrows when they see something written in that area.
If you are really concerned, find someone in the company to ask. But given the years, it being expunged, only being one and occuring in the US, personally I wouldn't worry about it unless I was trying to get a job that required all driving and they wanted to know your driving record... but in that case they'd probably ask for a DMV printout.
Generally, disclosures are for misdemeanors and felonies. Anyone please correct me if I'm mistaken.
