Actually

I have made 3 key changes and it seems to now work.

1) I have swapped to a laptop that runs XP SP3
2) Selected the LokPilot Silent BEMF since this Bachmann decoder was advertised
as silent and BEMF enabled.
3) Changed to another loco with the same decoder just in case my wiring was bad
;)

The Manufacturer ID is reported as 151 and the decoder ID 88.

I will investigate which of those 3 changes made the difference and report back
in case anyone else has the same issue.

Cheers

Phil