Wasn't he the commander of the fleet ? Maybe there we're 2 admirals (but that's not something that would be fine. 2 admirals... think of the disagreements...), and he is above it. So he wares a cape, to let him know who is in charge.
Orders of Knighthood do have capes/robes but these are only worn for special events. I find it surprising that since Sir Geoffrey was a Knight Commander of the Order of the Bath that he does not wear the Star of the Order on his uniform. I will have to find a picture of the Star of the Order for that particular degree. I do have some orders and decorations books in my study. I also find it interesting that he would elevated to this particular order of knighthood as this was the same order bestowed on another famous real world admiral - Horatio Nelson. Hmmm...a comparison of Tolwyn to Nelson in command style/leadership/strategy and tactics ....interesting idea for another thread.
WC2 was not the only time he wore a cape. I believe in the Grand Assembly in WV IV when Taggart introduced him as SAR Chief that he also wore a cape then. It was the same color as his uniform.
Order of Knighthood? Whats that?
BTW: In WC3 Tolwyn is a full Admiral, isn't he?
(Again sth strange that in SM2 he is Vice Admiral and in WC2 Rear Admiral. Did he get demoted as Maniac was?)