is this rear caliper salvageable?

[Bretty]

I hate to say it, but my bike lives on the street in London. So my whole ethos is, it must function safely (engine, brakes, tyres) but look like junk in order to not draw attention to itself and/or get stolen.

So I'm not fussed what it looks like, but will it work?

I'm going to go and reattach it to the brake lines to see if I can force the pistons out for inspection...