B(E)A must have been very pessimistic about demand to downsize the roginal DH idea to the T 1 and 2 series because while the lieks of Swiss , SAS KLM served smaller markets and no doubt saw the DC9 as much better fit the bigger Euro legacy carriers used 727s mostly 200s extensively and i would have thought that BEA had many routes , probably more than LH and AF where a 727 200 would seem to have have been ideal , LHR to Paris FRA MAD ARN AMS BRU plus the shuttles .
On the subject of UK missing out on markets because of state airline meddling and politics I recently read a book* about the whole 707 family which includes soem comments from Boeing engineering execs who visited Uk in lead up to the Comet 4 707 and Dc8 . Their veiw was that they didnt need to rush on the 707 since although the Comet 4 and incipient VC10 were good products the manufacturing facilities in Uk were so small and outdated compared to what Douglas and Boeing had that the Brits couldnt meet any large scale demand anyway and were not that skilled at marketing compared to the customer focussed Americans . Looking back with the benefit of hindsight and the typical lack of investment in engineering and technology in UK left me wondering how valid those comments might be as opposed to 'just blame the nationalised industries and the politicians of the day .
*The book is Graham M Simons -Boeing 707 Group a history