More than a comment, less than an answer, because I have no clue what camera/lens/film...
The car's registration plate sets it firmly between August 77 & July 78 - the letter is the year for old UK plates S=77 Ref: http://www.theaa.com/car-buying/number-plates
There's prestige in having a 'new' plate, so there's a high probability this was even shot before August using a not quite legal plate, for an advertising campaign set for August that year.
It's just wild speculation, but it wouldn't surprise me at all if they didn't just take the car to Woburn Safari Park-[Google Maps satellite view] & park up next to the giraffes.
It was the 70's. People were less concerned with animal welfare than they are now - although the animals at Woburn are used to seeing cars, as it'a a drive-through tourist experience.
Pic from their web site
The tree types & road style match.
There's nothing in the wheel hub reflections to hint they're not where they look like they are. In the 70's I wouldn't have liked to try airbrush the giraffe into the refection on the top of the car.
The only hint of 'fake' I think is the nearest giraffe, head & neck coming in from top right. It just looks a bit too convenient & looks like a hint of rim-light. It might also be covering a bit of ugly background where the road bends round the hill.
I found a larger version of the image on http://vsi.reactor.cc/tag/ваз
Which gives a slightly clearer reflection in the front hub cap, of, I think, one of the giraffes.
It is possible that reflection is actually of the 'fake' top right giraffe... which might make it 'not fake'. The child also appears to be looking up at it, so it might in fact be real & the rim-light possibly a sign they had some additional lighting.
The soft shadows really don't give much more of a hint than it's a fairly standard English cloudy summer's day. The sky might be washed out, but we do actually get almost totally white skies some days; very thin cloud, but total coverage.
As an example, this is a quick snap from my workroom window - taken today, just before noon, mid-summer. Typical British summer sky...