Might be the flasher relay, Neil. There is a separate relay for the normal indicator function, & one for the 4 way hazard flasher function.
The normal left or right relay is located under the dash on the drivers side, if you have the original unit in there it is a small rectangular silver (metal) item, with two connectors arranged in an L shape. It is mechanical in operation (it works rather like a set of points) rather than electronic - it can be replaced with a modern electronic item although you usually have to add an earth wire.
The hazard flasher relay is in the fuse box area.
Or, it could be the indicator stalk at the steering wheel, the connectors in there get crappy or just plain worn.
Tony
<font size="1">1981 TR7 FHC Cavalry Blue
1980 TR7V8 DHC Jaguar Regency Red - sadly sold!
1977 TR8 FHC EFI Factory development car Inca Yellow</font id="size1">