In the Classic should the arrow in the recirculation switch light when recirculate has been selected?

It does not do so on my wifes three year old that she has just bought.

If it does not light how does one know which mode one is in?

Might be due to the position of the air flow selector dial. I had my heating unit replaced last year (unknown fault - just died) - when dealer was demonstrating 'all systems go' before I left, remember him saying something about recirc not selecting when pressed, I think whilst air flow directed at windscreen (in order to prevent misting up which occurs during recirc in damp weather). So, try selecting it with different air flows positions dialled up (and with your hand shielding it from the light 'cos its not very bright!)

And if it comes on but goes off quite quickly it could be a fault with the flap motor.

Might be due to the position of the air flow selector dial. ...

Thanks. That was the cause. When checking I found that recirculate is not allowed in the demist position.