Ursus arctos middendorffi, adult female with cubs born 21st January 1973.
There were actually 4 cubs, although only 3 are visible in the photo. Unlike the brown bear enclosure, which is still in use, this deep concrete bear pit was quite small and very bare and bleak. It was next to the polar bear enclosure which was a small concrete oval surrounded by thick bars with overhanging spikes. The lion and tiger 'dells' were further along the escarpment and surrounded by similar bars, but at least they had grass and bushes giving some cover for the animals. Scanned from a Kodachrome transparency.
@gentle lemur
This Kodiak bear pit (which originally housed tigers) was always my least favourite Whipsnade exhibit but thanks for uploading the old Whipsnade photos which bring back many memories.
@Pertinax
I've three 1930s postcards depicting tigers in this pit; two published by the Zoological Society of London and a third published by the commercial postcard company J. Valentines.