Welcome to Flyertalk, Tse Wai Shun Jerry. It's great to have you here.

I think it's highly unlikely BA would fly LHR-MNL-TPE as a tag route - BA is not really interested in such fifth freedom routings these days, except in the Caribbean which is a very different market.

However it's certainly possible that BA could launch one of LHR-MNL or LHR-TPE with their new aircraft in the coming years. I'd think TPE the more likely of the two. There are a lot of other potential new BA destinations though, so I wouldn't wager much money on either of them.

There was also some interesting/amusing discussion about TPE opportunities in this thread last year: http://www.flyertalk.com/forum/briti...r-tpe-per.html