I believe here it is used as an adjective, not the name of a political party.

I think it's used as a reference to the UK incarnation of a political philosophy [1], which by no means has a monopoly on promoting the serveillance state.

https://en.wikipedia.org/wiki/Conservatism

Labour are not “The Conservative Party” but they are definitely (at the moment) pretty solidly a conservative party.

The surveillance state isn't an exclusively conservative idea though. It has a long and storied tradition on the Left as well.

I believe you're conflating "big-C" Conservative with "little-c" conservative.

The Conservatives (aka Tories) are conservatives. The Labour party are also conservatives as much of the voting public in the uk is small-c conservative and also authoritarian.