Originally Posted by AJLondon
By "ticket in J", do you mean a ticket in the NCW cabin, or do you specifically mean a NCW ticket with a J class fare basis?
If it is the latter then, having a quick look at the BA fares pdf for the LHR-SIN route, for eg. if you bought a J2BA you could upgrade to a A fare for under £200. (Upgrading from a CRT1 fare would be about a grand.) Similarly if you bought say a (insanely ridiculous!) JRT fare, you could actually "downgrade" to a F2BA1 fare which is substantially cheaper!
I'm not sure if you'll be able to officially upgrade thru ticketing/reservations from a I or D fare though.
Thanks
G-BOAC and
AJLondon for your prompt and helpful replies.
I have bought the ticket for my mother in the Summer Club World sale, so it is no doubt the cheapest of the cheap, and the lowest fare class possible. I assume that this fare is non-upgradeable.