Further to what was correctly said above in two posts about the ancestry dot com record set...
England and Wales, Death Index, 2007-2013
which, in any case, is a misleading record set title, as is typical with many of the record set titles on ancestry.
This is the verbatim wording of ancestry's information about that record set
"Original data: GreyPower Deceased Data. compiled by Wilmington Millennium, West Yorkshire."
"About England and Wales, Death Index, 2007-2013
This collection is a compiled index that covers approximately 55% of the total deaths that occured in this time period.
This index provides death details for people in England and Wales, specifically their name, gender, date of birth or age at death, date of death, and residence place at death. However, they do not include the General Register Office (GRO) reference information."
With the GRO birth, marriage, and death registration index records that are available online up to recent years as computerised records, the explanation for the reason for the cut off date of the availability of computerised versions of those records, which I've read about, says that the GRO project for the transcription and computerisation of those records was halted before it was completed, because the funding for the project was withdrawn.
That only makes sense up to a point though, because obviously the current records for the more recent and non publicly available online registrations are already on a GRO computerised database, so extracting the registration information from the GRO database shouldn't be a technically impossible or or hugely expensive task, if the will to do it was present.