I think I have sussed it, or at least found another problem!
Martin Page appears to have played three rated events.
Surrey Major in April 2009 where he scored 3/4 against rated opposition under his correct FIDE code of 418382.
He then played in the Surrey Major of April 2010 and scored 0/3. This was rated as Martin Page 406376. However, this is an error as this FIDE code related to Adrian Archer-Lock. http://ratings.fide.com/card.phtml?event=406376
. The ECF grading database tells us that it was Page who actually played http://www.ecfgrading.org.uk/?ref=11661 ... 1512505633
Finally, he played the Surrey Major in April 2011 where he scored 1.5/4 against rated opposition under the correct FIDE code.
So, the wrong code was been used at Surrey Major 2010 which is why these 3 games do not show against Page's record. As Adrian Archer Lock hasd a FIDE rating in April 2010 games against Page at Surrey in April 2010 were incorrectly rated as if they had been played against Archer-Lock. I suspect that it is this that has been corrected as these games should have been unrated. This will have a knock on effect on anyone who played Page at the 2010 event.
The matter is further complicated by the fact that the 1st part rating achieved in April 2009 is now more than 2 years old and so therefore is now discarded.
However this happened, it's difficult to see how any of this could be Coulsdon's fault.
Archer-Lock lost 30 rating points at Surrey in an event he didn't play in and this will have had a knock effect in all the tournaments that he has played subsequently.