I’m in the same spot as you, a couple of months ago I booked a return business seat to the Far East via HKG on Cathay for just over £2.5k, It looks like I need to go back again, I can’t find a seat on Cathay for less than £3.8k. At the time Cathay were even cheaper than Thai.
Exploring the alternatives (that still score BA miles) the best I can find are some dubious looking seats on Finnair’s old A340 for around £2.2k
I’ve seen BT has just posted a review of Finnair’s A330, but not read it, I’m sure it will be an improvement on tha A340
Curiously I stumbled across some special fares on Cathay via Copenhagen for £2.8k, perversely the first leg of the journey, whilst orginating in CPH, takes you back to LHR to get you onto the direct flight to HKG.
If you need to move from Bronze to silver this gets you 360 tier points and two qualifying flights all in one go.