Since adding the site info, I'd also Googled for the 'Monument Number 33025', and found it listed on another pdf file* on a page in [quotes in inverted commas]
"Durlston Head to Rame Head SMP 2 Appendix D - SEA Environmental Baseline Report (Theme Review)":
"Monument Number: 33025"
"Name: Chambered Tomb, 630m North West of Elberry Farm"
"Easting: 289319" [not sure why it's prefixed with a '2'?]
"Northing: 57329"
[That means the grid ref I supplied -SX893574- was a little bit closer in 'eastings']
"Area (Ha): 0.02007"
"Coastal Section: J"
*That is a very useful file for listings of monuments to go and explore in the Durlston Head to Rame Head area. I printed out two pages and each had 19/20 sites' refs.
No doubt someone will come up with a better listing for this site at Broadsands.
Something is not right. This message is just to keep things from messing up down the road