I think in fact all the points mentioned in Charles' and Lodovik's were messages were before the GLAM task force, in at least some form, when we discussed the matter. The term and concept of a "National Monument" does not exist as such in the UK, as opposed to other countries, in itself something of a problem. I believe the Netherlands has a single list, some 30,000 strong, covering all types of sites, buildings, and things. That is certainly not the case in the UK where (I forget the exact figures) when you add listed buildings to Scheduled Ancient Monuments and other types, you get well over a million, but for the most part without easily accessible listings. As Andrew rightly points out, these are not all centralized - listed buildings are by local authority and SAM's under different bodies for the constituent counties of the UK. The time available to assemble such listings, which seems to be a very large task, although in theory the information is available, was probably inadequate.
As well as photos, many Dutch NMs received WP articles, (also in English) apparently on the basis that NM's were inherently notable, but there are several precedents for eg UK listed buildings being held not to be notable, and the same would be true of the lesser sort of SAMs which form the majority (hut circles, medieval moats etc). We felt a rash of deleted articles as a result of a NM project might have a negative effect.
Overhanging all this was the 80,000 (is it now) mostly good quality, photos that are already on Commons from Geograph, that are still unsorted, or incorrectly categorized. Bearing in mind that many of the 326 photos in http://commons.wikimedia.org/wiki/Category:Wikipedia_Loves_Art_at_the_Victor... from February 2009 are still otherwise uncategorized, or not well categorized, we thought that pressing on with digesting the Geograph material was a priority.
In the light of this, and the number of other projects the chapter has taken on, and the lack of anyone pressing to lead the iniative, we decided not to involve trhe chapter this year, and I still think we made the right decision.
John