Hiya Chris,
Its from a Prehistoric Society report in 1935. I've just stared at it again and seen the haystacks in the background. I presume the images are from 1935 (photography being a bit basic in the C19th!), There is no date associated with the images, or indeed a photo credit. Unless of course the haystacks in the background are in fact iron age huts, and those celts were more advanced than we thought!!! ;-)
Looking at the other posts for Notgrove, it appears it was covered over in the 70's, there was a lot of stones kicking about in 1935, so I guess it was for the best. It's a cotswold type, so related to Waylands I suppose!
I posted the text from the report too. That's all there was on Notgrove in the report. I bought it from a second hand bookshop many moons ago. I can scan at higher res if you like, but they will have the 'moiré pattern' on them. My scanner is 'smoking' at the moment so you may have to wait a short while.
WF