N° 8 Mk I trainer fitted with an A. J. Parker 8/53 sight attachment

[Didier]

Some, at least, of them, had a shorter windage arm with less adjustment (because with .22 you were not going to shoot with huge amounts of wind). Some appear to have used the standard PH5C one, which may have been clearup of parts on hand.

https://www.rifleman.org.uk/PH_Service_sights.html#5A

Thank you for the explanation and the link.