Good news. Just had the lens delivered back to me by courier from Nikon
They made some repairs, plus a good clean and service to boot. As good as new now and QUIET too.Total cost was, as mentioned £100 , so given the cost of buying a replacement, I think this is money well spent!
Doubly so, as I use this lens an awful lot, PLUS I'm doing one of Nikon's in-house courses next week in Kingston-upon-Thames...so good timing too
Patrick