The ironic thing is I've probably spent more in the unforced shopping area at LHR T5 than at any of the others in the UK
Your irony may be misplaced given that the choice of retail outlets in T5 are unsurprisingly more upmarket than in STN or LGW! Boots and WHSmith seem to be the only outlets I'd use on a regular basis when shopping in the UK .... or have I missed something?