Thanks for the responses.

Am tied up at the moment and will respond properly later but to clarify re assistance request - the assistance was requested at the time of booking which at least a month out (I booked over the phone as the connection times on the website were very tight and I didn't want my mum to feel rushed). The request was there when we checked in and had no other problems with the wheelchair on the 4 flights.

The BA desk I referred to was the customer services desk in the South Galleries lounge.