That's a good question. As explained to me, Direct TVs is a national retailer, while Ashton TV is a local independent.
To match a local independent's price, the store must be within an eight mile radius of your nearest John Lewis branch.
I'm not sure the distinction is that clear, but I'd spent 40 mins on the phone trying to arrange this without getting anywhere. The employee I spoke to wasn't up for a semantic argument and I wasn't keen on antagonising a retailer that's gone beyond what constitutes excellent customer service. (You might argue that I was cheeky asking in the first place.)
FWIW, others tried this price match and failed also.