The old brain cells have come up with PH-DCH but I can't find the Viasa registration. Saw it in 1966 at Schipol when on a school trip to Amsterdam. It was destroyed in a hangar fire in 1968.
Re. the BA/Singapore Concorde, not sure it had 9V registration. I saw it take off at Bahrain at night around 1978. Most impressive seeing the re-heat at night.
The BA/Braniff Concorde was re-registered every time it went through Washington.