Kev :
I have done a bit more research on this for you .....
I suspect you are the owner of one of the previous models of Triumph Trophy !
This forum is dedicated to the "new" Trophy released in 2012.
PLEASE CONFIRM which Model / Year Trophy you have.Some earlier models ( such as the Trophy from VIN 29156 ) also incorporated a RELAY
into the Side Stand switch circuit, and a faulty relay could also be causing your problem.
These earlier Models DID have a Warning light that came on when the Side Stand was down.
( I can't remember now but it was built into either the Speedo or Tacho head
and was a red coloured mini image of a side stad in the dwn position ! ).
So, IF your Trophy was an earlier Model, I would suspect a
faulty Relay,
but I cannot offer any further help as to it's location,
other than seeing if you can trace the wiring back to it,
and maybe consulting Members of another Forum - try Googling "triumphrat.net/trophy 3 & 4"
You can also obtain a Service Manual with Wiring Diagrams here :
Manuals Library