Happy New Year everyone. I’m flying JNB-LHR-AMS with checked luggage, then need to get back to one of the London airports on a separate ticket. Cheap Y ticket but I’m a One World Sapphire.

I arrive in LHR at 07.30, the connect to AMS at 10.55, arriving 13.20. I would like to fly back from AMS at 14.50. Assuming no delay on the LHR-AMS, is a 90 minute connection too tight i.e. the long march to and from the D gates, collect baggage, check in for AMS-LGW? Is there any chance BA would allow me to take an earlier LHR-AMS if space available? Or should I book a later return flight to LON?