I seem to recall a point being raised a while back regarding the the release of steam from nuclear submarines during movements in the Clyde.

I just spotted the following post in the Clydesights blog:

ClydeSights: HMS VENGEANCE - S31

Which will take you to an excellent pic of the sub, complete with a clear view of the aforementioned steam venting from above the conning tower, which is also noted to still have the access platform in place for workers carrying out maintenance of the various accessories which are provided on the tower.

Yep, that is what I have seen a couple of times.

Your'e all no doubt aware that these ugly contraptions today aren't the first submarines to vent steam in the Firth of Clyde.  Steam driven submarines were tested I believe in the Firth prior to  WWI.  

Nice.

I don't think I've tripped over that site before

Dugald - see the short K.13 (1915) summary in Secret Scotland - HMNB Clyde

Thank you Apollo, I visited the site you recommended and found it very interesting. Yes, I remember the boat K13, and I see in your history of subs on the Clyde that she was the last submarine to be named K13... can't imagine them being so dingdongish as to call it that in the first place! There is a memorial in the Elder Park Govan, for the crew and the Fairfield employees (I may have posted this before, but i searched and couldn't find it). I think there is a mistake in the name of the Captain of the K13 and they have him shown on the memorial as having the VC. By the way, I noticed also in reading the history of subs on the Clyde that a depot ship is mentioned as having been stationed at Campbeltown... I don't ever remember this...I'm not saying there wasn't, just that i don't recall it. I recall the other depot ships mentioned.

I'll take this opportunity to wish you and all the  SeSco people, a Merry Christmas and a Happy New year! Cheers, Dugald.