I do know a bit about what a gunner did, or does, as I was a Royal Artillery gunner myself in the 1970s (24343393 = one thing you never forget is your service number!) I was 'number three', the guy that layed the gun (put it on target) and actually pulled the BANG lever; on the Troop Commanders gun. Actually I reckoned when I joined up that I was a lot safer firing at someone 10000metres away - so the gun I was on was the modern replacement for the 25pdr - gun, howitzer and anti-tank gun all in one - and the anti-tank bit meant close up!
'Ubique' is the motto of several regiments. The Royal Artillery full motto is 'Ubique quo fas et gloria ducvnt'; "Everywhere we go glory follows". The badge of the regiment, also used by several 'Commonwealth' artillery regiments is a Napoleonic gun and cannon balls.
According to Bob, the RCA was pretty much the same as the Royal Artillery, which for a gunner in a field regiment meant being mobile and staying close enough to the sharp end to support the infantry and take out anything that obstructed their advance with either high explosive or armour piercing shot, or laying smoke to cover them, or a mix of all of these.
The Canadian field regiments were equipped with the famous 25pdr gun, towed behind a CGT - Chevrolet Gun Tractor (yep - a CMP !). This gun was good enough that I still fired it in training in the 1970s
.
I do have some other stuff that Bob told us, but I'll have to find it amongst a load of junk. If I can I'll email it to you or post it here. I do remember that he was bombed twice - by the Americans LOL.