Thanks
TS, we did find it, although it was not as easy as we hoped since the signage is not great. If you stand outside one of the shops and look down the line of shops - there are no signs visible. You have to stand away from the line so that you can look along the front of the whole row to see the signs that are flat against the shop front.
Coupled with three people not knowing what we were looking for (two were shopkeepers and one was airport staff who turned out to be standing 30m from the shop but directed us to the far end)
On a lighter note ... I like this from Simon Calder:
Heathrow Terminal 5
When the sole tenant of a new terminal feels obliged to take out advertisements saying that only one in 10 of its flights is more than 15 minutes late, you know it has issues. But in the unlikely event that you find yourself lost in transit at Heathrow, try to make it inside this £4bn-plus public relations disaster. You can expect breathtaking views across Europe's busiest airport, classy shopping and the sense of space from a terminal operating at 50 per cent capacity.
Articel coparing a number of airports is here:
The airports that make you pray for a delay - This Britain, UK - The Independent