LHR-BOS and vv is a route I fly every 3-4 weeks
LHR-BOS - I've had a 100% OpUp rate since I've started flying BA on this route - generally on the 215 or 239. I've booked in WT, WTP and Club, taken POUGs and UuAs, hasn't made much difference.
BOS-LHR - I tend to get the 214 and with a success rate of 0%, however, on the 202 I'm back at 100% - though I've only taken that 2-3 times over the last 18 months or so