Thanks for posting this Dominic. How long ago was this?
I see they also have a virtual tour which gives a half-decent view of stuff like the ceilings. There's a self-drive option for the tour or I've done a chauffeur-driven one, if you prefer:
With regard to list descriptions - they are not intended to be an exhaustive schedule of listed elements of a building - they are merely a means of identifying a building. Once a building is listed the whole building is listed (though usually later, low quality works will be of less value). The quality of list description varies wildly as many were written in haste as part of a mass listing programme. The tastes of the listing inspector we're also highly influential in early entries.
With regard to English Heritage's involvement, they do not usually get involved in day to day casework for grade II listed buildings unless it is a very large or politically sensitive project; I'm not sure about Haringey, but most London Boroughs have delegated responsibility for Grade II buildings meaning that thought they will write to EH (they are legally bound to) EH will send back a standard response confirming that they will not be making comments.
At this point I should probably declare that I worked in conservation teams at for EH, London Region for ten years.