Hmm, interesting that the posed question is not being contested.    Have just contacted the author of said web page to see what further he has to say about this.
On another note, I believe I have found which of the five crew members was the commander of Holy Roller, and that would be Frank E. White.   Diary entries have his rank as Major, and his appointment as 
2IC.  
http://heritage.canadiana.ca/view/oo...657/74?r=0&s=6
This means his Sherman would be the 2nd vehicle in the 
RHQ squadron, and if it were to carry a radio call sign, it would be 
Z2 as illustrated here:
 
A very detailed breakdown of Armoured HQ can be found here:
http://www.ww2talk.com/index.php?thr...1/#post-290158
... but essentially this is what I used:
Tank 1
Lieutenant Colonel, Adjutant, Sergeant, driver mechanic, driver operator.
Tank 2
Major (2IC), Regimental Sergeant Major, operator RS, corporal driver mechanic, driver operator
 Tank 3
Subaltern, Sergeant, driver mechanic, gunner operator, driver operator
Tank 4
Intelligence Officer, intelligence corporal, gunner operator, driver mechanic, driver operator
regards,
Jack