Pale crag martin to do so, it would cast doubts on their specific distinctness. There are several subspecies differing in plumage shade or size, although the differences are clinal, and races interbreed where their ranges meet. The pale crag martin of the nominate subspecies "P. o. obsoleta" is 12–13 cm (4.7–5.1 in) long with light brown upperparts, becoming paler on the lower back, and a short square tail that has small white patches near the tips of all but the central and outermost pairs of feathers. It has a pale grey throat, upper breast and underwing coverts, and the rest of the underparts
Colour Strike programmes (shot in colour), the colour signal from the telecine machine had to be switched off in the vision mixing desk before being recorded to tape, but this was partly unsuccessful, leading to some film sequences being recorded with an odd array of pale colours (as for items where the colour is a mix of two primary colours, only one primary colour would show). This is prominent in the second series of "Hadleigh", for example. The first "Coronation Street" to be broadcast in colour was transmitted on 3 November 1969, but due to the strike, some 1970–71 episodes, including the