See my post of 9/3/10. Have just entered a dummy booking from ABZ-LHR-LAS with the return flight on 2/3/10. When I tried Premium Plus with an MFU to J (paying cash and MFU with 25K miles) the return flight arrived into LHR at 14.05 on 3/3 but the first available flight to ABZ was the 06.55 on 4/3. When I tried to book J using an Amex 2-4-1 the return flight to LHR was the same but I was given the option of the 17.15, 18.05 and 20.15 to ABZ on 3/3.
I would have thought that the cash/MFU option was more lucrative for BA and given that the seats on LHR-ABZ are basically all economy .(any time I have booked F or J redemptions before no preference is offered on seats for the domestic leg although lounge access is available – i.e. redemption passengers are usually seated towards the rear of the plane) I cannot understand why seats are not available on the domestic leg of such journeys for all redemption awards.