The Pension Tracing Service can help. It holds details of almost 200,000 UK pension schemes and provides a tracing service free of charge.
You can contact them at:
The Pension Tracing Service
The Pension Service 9
Mail Handling Site A
Wolverhampton
WV98 1LU
Telephone: 0800 731 0193
Website: www.gov.uk/find-pension-contact-details