I would like to thank you all for the very useful responses. Specially for the wiring diagram. After checking the horn push which as you said had a 12 volt feed and then checking the horns which did not I deduced it was the relay, but only with your help. On my MX5 the relay was in the engine compartment N/S/inner wing by two others. Brought a new relay from Autolink MX5 fiited a few minutes ago and woke the whole household up. Thanks again for your help.