There were 9+ (a Hurricane sneaked in) Merlins flying for the the Spitfire 60th at Duxford, and that Cat you saw was the same company - this one's the replacement...
I think the Shoreham tail-chase was the anniversary year too, and thinking about it I think it was billed as a Merlin tail-chase with hurricanes and a Buchon included, there was also a weirdie that I was sure was a typhoon but turned out to be a really late model Spit with a similar chin intake
