Some valiant guesses but my map remained enigmatic to say the least. Top of the map is North. The sandy coloured road is the main route from Belgorod to Oboyan. Tomarovka is in the bottom left hand corner. So, despite looking misleadingly mountainous, this is the southern flank of the battle of Kursk and is the latest incarnation of the Steel, Steel, Steel! design.
The German unit with the British 25pdrs is the 57th Infantry Division, part of Army Detachment Kempf. According to the Dupuy Institute data, they had 8 87.6mm Howitzer (e), otherwise known as 25pdrs. I don't know the source of these but possibly Dunkirk rather than N Africa.
I have often wondered what happened to the kit abandoned in 1940. I have read, and seen photos, of Bren carriers in use by the Germans on the Eastern Front. Captured from the British or the Soviets? There is also an interesting German flamethrower unit armed with British MkIV cruiser gun tanks. Everyday is a school day!