A thorough bargain in my opinion - £3.99.
Yes, it's a spin off, but as far as spin offs go I feel this is a pretty good one, but it is definitely not on par with the true Spooks series. Also, this series only had 6 episodes as opposed to the usual 8 or 10 you get.
This is available at Amazon for £3.98, but obviously would need to be purchased with something else of £1.02's value to qualify for free delivery.
Some people might not be interested in this, but I am sure there will be a few that will be, especially at this price.
(It is up on HDUK as £2.93 at 'lovefilm', but I can only find it at £4.31, hence I put this up).