Now please bear with me - I'm not after a good seat just for the sake of it.

In June me and my to-be-better-half fly (economy) SQ Manchester-Melbourne, then United to SF and the Caribbean, then British Midland back to the UK. It's a RTW for our wedding in Oz and then honeymoon.

I'm 6'6" and have developed a really bad back strain (a short hop from Frankfurt to the UK last week was very uncomfortable) and I'm getting really quite concerned about sitting in a chair at the wedding with back spasms. Then there's the honeymoon of course, since I'm not going to the Caribbean to miss out on the scuba!

So an upgrade would be great, and extra legroom is a must. Of course we can turn up hours before departure and hope for the best, but how do we improve our chances to near certainty? I guees if I mention my back they won't let me near the bulkhead as I could not lug the door around in case of emergency.

So some advice would be much appreciated.