Alternatives to 'standard' derailleurs ...

[Zimmerframe]

It's my car...

The sprocket broke because foolishly, I attempted to lock the engine in order to do up the hub nut by jamming a screwdriver through the cam sprocket. Nothing seized except my judgment.

I've passed your details along in case they're looking for any help ...

 

[RustyMTB]

Wouldn't fancy putting the cover back on that.

 

[cappuccino34]

It's my car...

The sprocket broke because foolishly, I attempted to lock the engine in order to do up the hub nut by jamming a screwdriver through the cam sprocket. Nothing seized except my judgment.

I couldn't think of an actual failure mode that would cause that damaged naturally besides a seized cam, and I hadn't seen the chain hiding down the back. I hadn't considered that it was caused by baffoonary. :-D

 

[RustyMTB]

It's buffoonery, not baffoonary, you buffoon.