Spitfire 20mm Cannon Shells…

I have a couple of spent 20mm cartridges, which were given to me by my late grandfather.

I remember him telling me a story when I was young, about how he retrieved these cases from a field behind his house in Netley near Southampton, after he watched a Spitfire attacking a ME110, which he said crashed a few miles away, heading towards the Woolston area of Southampton.

I’ve no idea of the date, but the two cases are marked on the base,

1942 R H Z.0
1943 R H Z.0

Can anyone shed any light on this event, and/or the meaning of the markings on the cases?

Another small story….
I moved into my late grandfathers house with my parents in 1960 something, and next door lived my Uncle ‘George’. I remember him telling me he worked at Hamble during the war, repairing damaged Spitfires.
He provided me with a complete Spitfire canopy to play under. I recall it being cracked, and the thick front section was very heavy to play with.
I also had an instrument of some kind…..ammeter or something like that.
I wish I’d kept those…..

Regards