Thanks for heads up nippymog and glad issue appears to be sorted with replacement relay.
I still cannot see how the main beam fuse 16 could blow though as it's after the relays, and the wiring schematic for both early and late M3W's is very clear on this. There is a main beam relay fuse 7 (20amp) however, that feeds the flash relay (both coil and main contact) which could blow this fuse if it caused an internal short though.
The issue of main and dip beams on simultaneously is a red herring as each are fused individually.
