We just discovered by chance that my husband has not had NI contributions credited for the last 6 years since being transferred from IB to ESA. We will chase it up, and sort it out, but thought others should know in case this isn't a one off. It's fairly easy to check your NI history at www.gov.uk/check-national-insurance-record . Would be a shock to get to retirement age only to discover you aren't entitle to a pension!