Having checked my log book I didn't operate a NCL-LGW-NCL in March 1991 so it wasn't me!
The 146s and crews were moved to LGW. Again, having looked at my log book I was still operating the odd LGW in June 1992 and the odd NCL-MME-AMS-LGW and return during June. If memory serves me correctly the 1-11s became part of the operation to NCL as you mentioned. The 146s were heavily involved with Berne, Innsbruck and Chambery (winter) from Gatwick and we also spent quite a lot of time in Berlin.
Having finally sold our home in the North East and bought a new one in Sussex I was made redundant three weeks after my new mortgage started. 😠
Apart from that they were great days!