https://www.gov.uk/tell-employer-or-college-about-criminal-record/what-information-you-need-to-give

Every conviction is recorded but most get removed from basic public records after around 2 years. Serious crimes may never get removed or may take longer to be removed.

If you apply for a job working with children or some other vulnerable group then the employer can usually see the removed convictions as well, as they may be relevant even if removed from the basic records.