Pontius
Apparently ,from those few we know of who have returned, it is reinstated to what it would have been had you stayed. Constant chatter overseas is that the situation is being reviewed, with one possibility being that we would regain the increments , but only based upon our current remittances .
Since Tony Blair's administration quietly disenfranchised us some years ago ( and therefore there are no votes in it) you can draw your own conclusions as to what the likelyhood of that is.