So I was in Jessops in Cardiff (the only one with a Pro Centre, and actually a pretty good one at that).
Mentioned that I was looking to buy the 400L at some point and he did a stock check and the lens comes up as "obsolete" on their computer.
There are apparently only 2 things that cause this;
1. Jessops have decided to stop stocking the lens (which is apparently UNLIKELY as they sell quite a few of these)
2. Canon have commenced construction of the new/replacement 400L lens.
A quick call to Jessops head office by the pro centre rep confirmed that the replacement is likely to be in stores at the start of april/end of march.
This has also been confirmed this afternoon by pro centre reps at Jacobs Digital and Calumet.
The new lens will apparently mean that the mkII lens will drop to about £3300 to clear remaining stocks.
Have at it with any info re: the lens... All i've heard is that they've updated the USM mechanism and completely re-engineered the IS electronics to make it even better than before.
All this aside, I'm probably going to go for a mkII lens for the reduced price.
Happy Chrismas Canon Fans!!
Get saving now.