What is the tune on isle of man tt races itv 4?

The tune you're thinking of is likely "Manx Grand Prix", a traditional Manx folk tune often played during the Isle of Man TT Races.

While it isn't the official theme song for the event, it's been used for decades and is closely associated with the races. It's played often during the races and on the ITV 4 broadcasts, creating a strong connection to the history and tradition of the Isle of Man TT.

There might be other tunes played as well, but "Manx Grand Prix" is certainly the most iconic and recognisable one.