The UK Houses of Parliament netblocks are publicly listed:
https://apps.db.ripe.net/db-web-ui/lookup?source=RIPE&type=inetnum&key=194.60.0.0%20-%20194.60.63.255 https://apps.db.ripe.net/db-web-ui/lookup?source=RIPE&type=inetnum&key=82.111.122.128%20-%2082.111.122.135 https://apps.db.ripe.net/db-web-ui/lookup?source=RIPE&type=inetnum&key=82.111.119.192%20-%2082.111.119.199 https://apps.db.ripe.net/db-web-ui/lookup?source=RIPE&type=inetnum&key=82.111.126.144%20-%2082.111.126.159 https://apps.db.ripe.net/db-web-ui/lookup?source=RIPE&type=inetnum&key=212.161.99.0%20-%20212.161.99.7
They were unwilling to reveal the UK parliament web proxies in an FOI request, so here's the list of every IP address that has made a Wikipedia edit from the UK parliament netblocks. Guess the proxies.