I dont understand what you mean by asking this...
There are plenty of 'luxury' brands showing at LFW (Aquascutum, Jaeger, Mulberry, Paul Smith etc etc) that account for a large part of the British fashion industry, why wouldnt they have a place showing at LFW?
Any fashion week is essentially a trade show for luxury goods.
If your talking about brands with 'fashion kudos' there's still Christopher Kane, Giles, Peter Pilotto, Todd Lynn, Marios Schwab etc etc etc etc
I wouldnt say Gareth Pugh was any more of a Luxury brand than the above.