LGS6753
Not true - most BHX passengers fly on low cost airlines (MON, Baby, Ryanair, TCX and TOM)
I think it depends what you call a low cost airline. TCX and TOM are IT flights, with with a few seats sold as schedules. MON aren't a genuine LoCo - the only ones in your list that are (were) are Baby and Ryanair. All airlines need to be as low a cost as possible, but really of that list Ryanair is the only remaining real LoCo.
OltonPete will probably be able to provide the stats, but I would say that LoCo really provides quite a small share of the cake, in comparison with other regional airports - such as LBA, LPL, BRS, EMA.
As regards the question of yield, I'm sure I remember it being claimed many years ago that NEC and ICC related inbound business traffic provided quite high yields on business routes, but in this day and age, why would any responsible business allow it's employees (or directors) to fritter away the company's travel budget flying business on a 2 hour inter european flight - I know mine won't.
I guess that those with more money than sense in London may have different values.