Must BKK be after SYD or can it be before Australia?
If it can be before Australia, then I see two options:
A 4-continent Oneworld Explorer such as GLA-xLHR-ICN-xHKG-BKK-xKUL-PER-SYD-xJFK-xLHR-GLA
A 4-continent Oneworld Circle trip such as GLA-xLHR-ICN-xHKG-BKK-xKUL-PER-SYD-xJNB-xLHR-GLA
Base prices are the same for either option:
Economy GBP2100
Business GBP6200
First GBP11071
Prices should be lower from either Norway or Egypt if you can position there
Of course with either option you can add on more flights and stopovers
The Oneworld Explorer should be bookable on-line on Oneworld.com
The Circle Trip will need to involve a travel agent or ring the airline