The hippo sculptures on Garth 22 have been a feature of the Garths estate since their inception in the mid 1970s. The history is a little hazy, but it is presumed they were installed as part of the local authority housing development to provide aesthetic value and unique amenities around the New Town. This was a fairly common practice in New Town estates, with animal cousins in Glenrothes as well as Walsall and Milton Keynes.

The designer is technically unknown, though it is presumed they are the same moulds designed by Stan Bonnar, a Scottish artists who created identical hippos at Glenrothes, Scotland. Apparently Bonnar was not consulted about the Killingworth Hippos, with the local authority here simply buying up the designs. There is an excellent documentary on Scotland's public art featuring Bonnar's new town Hippos here: https://www.bbc.co.uk/programmes/m00124rq

Anecdotally, the hippos are thought to be the last survivor of other installations around the estates at Killingworth. However, I'm struggling to find "concrete" proof of this and I'm continuing to research if there were any other installations. Apparently, each Garth had their own.

Unfortunately there isn't too much information on the Hippos out there. I've scoured the newspapers and it appears little history or information was recorded on their origin and why the local authorities chose them and how they found the moulds. Give a shout if you have any more information on the Hippos. Also, please respect the environment if you visit - It is in the middle of a residential estate.