It’s worth pointing out that Zulu Dawn had only been released in cinemas in the previous year, so to have a television premiere in that short space of time is very rare when it’s usually a three or four year gap.
It is probably a commissioned tune and could be Alan Tew, John Shakespeare, Don Jackson or Mike Vickers who composed it, it is probably gathering dust in a room of records and film reels, which were moved before the closing and demolishing of LWT's Kent House London Studios in 2018, so an ex LWT employee might have a copy.