Could that second numeral be a “7” rather than a “1” – did 7s have a vertical section at the bottom at that time?

Roger Smith.

Here’s a photo of K2227 https://www.flickr.com/photos/42836978@N02/6233384137/in/photostream/

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On this website you can find K2196 under RAF College:
Bulldog IIA – K1693, K2166, K2195, K2196, K2212, K2213, K2862, K2948, K2950, K2951