He was part of Dredd's team at the end of Every Empire Falls...
Was he indeed! I'll have to arrange a re-read, because I've no memory of that at all. I suppose I should have guessed, since I think only Mike has used him (or any of the Dredd clones, other than Rico?) since before Chaos Day.
Complete aside, but do you think Kek-W is going to throw clones into the mix in Deadworld at some point? We have the not-Judge Child, not-Booth, not-Lopez, not-Spikes, the actual-Sovs etc etc... could there be un-corrupted Sidney clones out there to challenge him? (I still insist on reading Death as the Deadworld iteration of Dredd, not Ava Eastwood, despite the very obvious parallels and the name).