With the Philatelic Bureau not treating change of source or year code as a new issue I have just realised that I have missed a whole pile of NVIs with different codes between 2009 and 2011. I get them now on a standing order with B Alan (Mike Holt also offer this service) but I have two whole years to catch up with and there are a lot :(
There are also some variations in the types of slit with, for example, a De La Rue 1st gold MBIL appearing with both type 1 and type 2a slits.
Dealers are also listing many shifts of phosphor and iridescent layers, (almost entirely down to Walsall's booklets!) These are often very pricey but outwith my own sphere of interest so I haven't catalogued them. I have tried to include every other intended change, though. See the NVI page at this link.
The NVI list has now been split in two. The 'less security features' issues prior to 2009 and a couple of later stamps - the 2010 EU and World NVIs - are in what should now be a closed list with the second one covering issues from 2009.
Now, to try and source those missing items at a reasonable price...