Monday March 30th, 2009
It would appear that the Deluxe and former listed as Signed Edition of Rides a Dread Legion found on HarperCollins UK website, has been removed from the site, so we can only assume that it is no longer going to be produced.
In addition to this, the Signed Edition of Rides a Dread Legion found on Amazon UK, which appeared on the 21st February 2009 and was supposed to be shipped 15th March 2009, has not yet been shipped (Unless you know better), so again we can only assume that it does not exist.
UPDATE: 17 May 2009, The Amazon UK signed edition has started to appear see Amazon Signed Rides a Dread Legion