I reckon that would be a question for @Pertinax or @Tim May - although I have guidebooks from around this time, I don't have them to hand at the moment to check the maps within.
@Lafone From memory there were two 'dells' as they called them, one for Lions and one for Tigers. As TM said, they were old chalk pits, now grassy and with hawthorn trees growing in them. Very naturalistic though the effect was somewhat spoiled by the high barred fencing with curved overhang that surrounded them. But an early attempt at a 'wild' situation. I think there are now open grass spaces where they used to be.
The high barred fencing with curved overhang, that "Pertinax" refers to, obviously made these two big cat enclosures look very old fashioned by today's standards. However I think they made better exhibits than the currrent lion and tiger accommodation
@Pertinax
I also preferred the Wolf Wood when it was where the tigers are now. That wasn't the original Wolf Wood though; the original was close to the brown bear exhibit.