In reply to my own question, I just found this from BALPA.
Cpts £52,500 - in pension scheme
£54,700 - not in scheme
F/O 300 hrs 737, 2000hrs TT
or 1000 similar jet, 2000 TT
or 2000 TP 500 PIC - £37,400 (year 2)
F/O < 500 hours 737
or none of the above
or non type rated - £27,500 year 1
- £34,300 year 2