Sadly, there's no modern car that's really as easy as the Capper to do.
Where do I put this 15mm spanner on the aux belt tensioner? I only ask as it's a 1/2" square hole. And before you scream "use a 1/2" drive ratchet or T bar", you can't actually get one inbetween the tensioner and the inner wing.
Doesn't alter the fact you need the special tool to do it.
The old one is sat in my shed, awaiting dismantling.