I went to the recent 75th anniversary Chipmunk event at Old Warden. Entry was via a long winded route through the estate rather than just through the gate by the hangars. Tickets were being issued by staff on the entry road who had a hand held card reader. Wishing to support the charity, I asked if I could gift aid my donation and was told they did not have the facility. During the day I called at the gift shop to ask them the same question and was told gift aid could only be done with online bookings.
I have paid at the ticket desk at many museums who have been only too happy to accept the extra money that gift aid brings. Old Warden must be either too wealthy or too dis-organised to turn down the chance of extra income.