As a consequence of the privatisation of British Rail, the Class 91 fleet was entirely acquired by the Eversholt Rail Group, which had leased it to various train operating companies. Between 2000 and 2003, the whole fleet underwent a refit (Project Delta) to improve reliability. The Class 91 units were refurbished at Bombardier Transportation at its Doncaster Works. This has resulted in the renumbering of the fleet from 910xx to 911xx. During this time, GNER hired in Class 90 locomotives to provide cover.