Based upon Worf's comments/recollections I have done some more research.
Worf is correct, and my comments about 'last visits' were in error. I said that the last Indian AF L.1049s to visit the UK were in September and November 1973 ... but I was wrong.
BG583/G visited 0n 4th June '74 and again on 7th June 74, and then the final visits (by BG583/G again) were on 26th Sept '74 and 28th Sept '74.
There was also an earlier comment about visits by Pakistan AF aircraft. There were Pakistan AF C-130s at Northolt in May and June 74, and the comment (at the time) was that these were the first visitors from Pakistan since 1965.