[JAS84]

Looks like they used LWT and Meridian's idents, and Media Merchants, United, and Scottish's endcaps. Though perhaps Scottish should've been represented by their ident too, as that endcap reads A Scottish Television Enterprises Programme, which is immediately followed by Programme for ITV at the bottom! Had they used the ident, it would've just said Scottish Television, and not had the redundant instance of the word Programme.

I'd say LWT designed this composite as that text at the bottom matches what their own endcap used at the time.