Everyone thanks for your suggestions.

number_6 that's a great sugestion of going via HKG. I lose out a bit because the fewer miles mean 20 fewer SC (for those of you who are QF freq flyers), but the connections are better and I save 8 hours in time. There is a QF flight from LHR to HKG at the same time as the CX one, but the QF flight leaves from T4, which is where the MCT flight arrives. (Seems odd that CX is in One World, but leaves from T3?) The QF flight is an easier connection, I would be able to use the MB spa, etc. Plus I get double points for flying QF as opposed to CX (which makes the long haul in QF J worth it), although I would love to fly CX J long haul one day. The Pier is great and HKG is a good airport for connections.

The CX flight to DPS on the day I'm flying is a 2 class 330. I assume that it will be regional J? (The weekend HKG-DPS flights are in a 3 class 774, but my schedule is not flexible enough to change to a weekend flight.)

If I fly via HKG instead of NRT, then my travelling time is shorter, but the HKG-DPS flight still leaves around 30 hours after I book in at MCT. I assume collecting my luggage in LHR and checking it in straight away to DPS would be my best bet?

Thanks again.