Thanks everyone for your input. No the aeroplane is not in a hangar with other aerplanes its in my driveway outside my workshop. It could well be a part from something out of the workshop. I have been working on the electrics ie; distributors, coils, spark plug leads etc so wanted to be reassured that it wasnt something from any of them.
An instructor of mine told me the story of him getting in a cub one day and finding a washer on the floor. The pilot said, "ah it doesn't look important, ignore it", so they did until at 3,000 feet enroute, the rudder cable disconnected from the pedals. They had a very interesting landing some of which was on an airstrip.
Hence my paranoia.