I haven't seen a 'National' Petroleum sign for quite some years (no surprise), but seeing that one has brought back a mini-flood of memories of seeing them in many locations back in the day, they were yellow/white on blue if memory serves. Glad to see that London Transport (TfL now) have kept their iconic signage.
I'm glad we've been able to put to bed the PanAm DC-8 landing at Blackbush possibility ;-)