I've just noticed that Avios E-Store are offering 8 Avios per £1 for a Hilton purchase until 10/10/16 (tonight!). An excellent bonus on top of the current sale. Unfortunately I've only noticed 3 hours before the end. I think this may have gone unnoticed by quite a few people. For comparison, the Virgin store is offering 6 miles per £1 and Gate 365 doesn't have Hilton.
As of this morning it's now 6 Avios per pound. Might want to update your 'Hilton cashback options' article from earlier this year, when avios.com didn't even offer it https://insideflyer.co.uk/2016/05/hilton-cashback-options-disappear/
Avios.com E-Store have raised the earning rate on Hilton bookings from six to eight avios per pound until 3rd September. A great deal, especially with all those Hilton we're booking to get the 10,000 avios... and all the other offers it stacks with!