BA 757 G-BIKA to IKZ and MRA to MRJ.
In fact towards the end of these deliveries, BA was buying used C engines from Eastern, as Eastern were re engining all their B757 with E4 engines, and fitting them to new B757s at the factory.
BA did not see the need to re-engine as the average stage length/shuttle routes was short, even though the E4 had 10-15% lower fuel consumption than the C.
BA finally went for the E4 engine with PEA onwards which was originally bought for charter subsidiary Caledonian, and needed ETOPS approval for MCO.
All subsequent BA deliveries were E4 engines, because there were no more C engines
Monarch Airlines
G-MONB-D delivered with 535C engines (but all later re-engined with E4 engines)
G-MONE and after delivered with 535E4 engines
Air Europe
G-BKRM, G-BIKF, G-BPGW, G-BLVH delivered/leased with 535C engines (and retained)
Later Air Europe and Air Europa deliveries had 535E4 engines
LTS
D-AMUR-T delivered with 535C engines (and retained)