In reply to MrsBuggins:
So I've previously done some business research into their business model, here are a few things to note.
Discount card: This costs £5 and think of it sort of a Tesco Clubcard that you pay for and you receive the benefit there and then, rather than as reward points. The benefit of them having this card, which they expect 90% of their customers to hold, or purchase at checkout, is that it logs all your purchases to your profile, to inform advanced stock making and promotional decisions. This data is extremely valuable and contributes to why they can afford to discount their prices over other competitors.
Product range: Their bread and butter and main profit come from their own-brand outdoor and camping range, I believe it's currently called Freedom Trail but it is also sold under other trademarks. The huge profits on these items mean that they can discount and compete with other retailers on things like climbing equipment which draw in the punters.
It's still laughable to go into my local store where none of the staff have any climbing knowledge, also, stocking a range of quickdraws which they only seem to stock one of each. It's a mess but that does mean hidden bargains can be found!
Sources - CMA Mergers & Acquisitions Report between JD and GoOutdoors, annual reports of both companies and additional material