There is some general information on these sort of clauses here:

http://www.roydens.co.uk/content03.htm

and here:

http://www.personneltoday.com/articles/2006/12/13/38604/repayment-clauses-payback-time.html

Which seem to imply its down to the detail, and therefore you need professional advice (I’ve never dealt with Acas, but do the provide specific advice for this sort of thing or general in principle?). There may be a couple of things in your employers favour: (i) the amount repayable reduces over time; (ii) they left it flexible to they didn’t have to recover anything – so the “severity” of the breach could be considered;

Al, Poly how could this debthave arisen after the email?

If you were acting for the company I think you would be arguing that the debt did not arise until 18/11/11 when the employee actually left. Certainly it couldn’t arise prior to him handing in his notice, so if the date preceded this (it wouldn’t be unusual for such things to be calculated to a month end as otherwise you don’t know which systems are up-to-date) then it certainly would be true.

Not buying that!

Update:

Just spoke to ACAS; their view is that I have no real chance of keeping them money.

I received the money with clear upfront statements saying that I’d have to pay it back if I left, and this included them saying they would claim it back from my final salary (and request further money if that wasn’t enough to cover it).

As for the email they sent saying that I didn’t owe them anything; he said I could get a legal opinion on it, but most it is most likely that they will be able to point to it being a mistake, or that the person who sent the email wasn’t in a position of knowing all the facts; i.e. it doesn’t change anything.

Bugger.

He did say that if I wanted to be slow about paying them back, that is another matter, but that I should be careful to not let it escalate to the point of CCJs and debt collection agencies as that would just be a big mess.

Pay up, or ‘lawyer up’? (to use an horrible Americanism)

Dave