What would it be? Say for about £1k.

Whatever you can find on this page that fits

http://www.paulscycles.co.uk/offers.php?cat=1

It will probably have a Giant sticker on it

Reign, Trance, Yukon, Anthem etc

Anthem would be a decent starting point

Anthem or Trance X.

Light in this context meaning "not very" then?

😉

Given that topic title, I can only think of Keith Bontrager's rule of thumb!

entry level anthem and upgrade later

Boardman FS bikes come in at about as light as can be done for the price point. However, I'd go with Drillski's recommendation, or similarly with a basic Scott Spark or Commencal super 4.

Second hand Epic/Anthem/Top Fuel or something if light really matters. It'll be >30lbs otherwise most likely.

Definitely need to be 2nd hand to meet any reasonable definition of light.

Cheap and light? Never gonna happen.

I thought the 2009 Spesh FSR XC was under 30lb – although maybe only the higher spec ones that are over £1k.

Nope, it's not!

entry level Cube AMS? Although I think they've gone up a bit due to currency.

It all depends on what you think is light. Some would say my 32lb Pitch is light (granted they wouldnt be weight weenies) others would say my 19lb Trek road bike is heavy.

Do you actually want a light bike or just a bike that isnt heavy?

If its the first one then you have little choice but to go second hand. If the second then anything under 30lb will do like an FSR xc.

erm, njee20……bikeradar has a review of the 2009 FSR XC pro (which admittedly is over £1k as RRP, but it weighs……27.4lbs

Link here:

http://www.bikeradar.com/gear/category/bikes/mountain/product/fsr-xc-pro-09-33623

and click on 'full specification' on the right.