That is interesting. The same site shows the other two field regiments of 50th Division, 74th and 124th as having M7’s in June 1944 while the 90th had Sextons. So there were in fact two regiments of Sextons landed in Normandy on D-Day, the 90th and the 86th.
Update
The pages below shows that the 147th Field Regiment also landed on Gold Beach on June 6th. The site states that it was an SP unit but dose not indicate the type of guns.
http://www.ra39-45.pwp.blueyonder.co...uro/page3.html
http://www.ra39-45.pwp.blueyonder.co...d/page147.html