Thanks, that's very useful. When I looked at ITA I only saw the R fare, not the D. But I'm fairly new at using it so I clearly don't know how to get the best out of it.

It's a shame it's so obscure when booking on the BA site - or maybe it's not, and I just don't know where to look. I did two dummy bookings - one requesting fully flexible business - and got an R fare and a D fare. But the information given seemed identical, in terms of change/cancellation.

However, looking at what you've given me, I've gone back to ITA and I'm really confused about the cancellation rules. On BA's website it says (for R class) "there are no cancellation fees". On ITA it says (apologies for the caps) "A REFUND WILL BE MADE TO AN AMOUNT EQUAL TO THE UNUSED PORTION OF THE TICKET LESS ADMINISTRATION FEE AND APPLICABLE VAT"

So is an administration fee different to a cancellation fee?

I'm particularly interested in cancellation, because I want to cancel this if an LHR-CPT award flight comes up to replace my current LHR-JNB award flight.