Lost the Horn

[supercrispy]

Found out the other day that my hooter had stopped working. Not sure how long its been like this. Fuse (No.1) is ok, tried shorting-out the steering wheel button but still no parp-parp, wires in front wings look ok. The wire (there's only one)to the button seems very thin, is there a relay (not shown in handbook). Has anyone else had this problem? Could it be the earth to the steering column? Any thoughts comments and experiences greatly appreciated (hand operated trumpet type air horn screwed to door mirror not considered an option)

[Tonto]

But its a genuine TVR part !!