Good find and cheap! I replaced my OE ones on the ZS with these as like you the socket became soft and oval. The F has the original ones and they are going the same way. I have also had to replace a few others on peoples cars using an impact socket to remove the nut. Now I have splined socket ones as I run Inovite rims on the zed.
2000 MGF 1.8i SE Wedgewood
2002 MG ZS200 Trophy Blue
1999 Land Rover Discovery series 2 TD5