I can only speak for myself and what I saw when I lived there in the sixties.
The gun ALWAYS being towed around by the AEC Matador was the Bristol Bofors guns as per the picture. All in sand colour. I know as Peter said they did a stint at Dortmund BAOR and raised a few eye brows as most of their kit was 10 years behind the times, but very much operational and in good capable hands.
The guns on the parade square look heavier agreed, but still think they look British.