Not quite. BMA tried LTN-GLA via EMA and LBA in 1970 - didn't last that long; a mix of BAC One Elevens and Viscounts.
It's all coming back now but that Luton-Glasgow service via Leeds/ Bradford was by a Dan-Air 748 which started in April 1972 unless BMA also ran a service which I can't remember.
The service run LTN-LBA-GLA-LBA-GLA-LBA-LTN. Doing a search at the website Dan-Air remembered the website says jets were introduced later on.
Capital appears in my 1989 timetable running a service to Belfast using Short 360's I seem to remember they also operated 146's in this service.
Capital Airlines (UK) - Wikipedia, the free encyclopedia