the original Inverscotians were:

Macgregor Kennedy

Randolph (Kennedy?) - I think he was MacGregor's brother, but he was banished for a misdemeanour I believe!

Seamas McNeill (College of Piping Otago St) - he never came to the Cowal gatherings

Rab (Sharples?)

Roy (Campbell?)

Terry

Dave

Jimmy Jennett

I thought there were nine, reduced to eight - but maybe I was wrong? - am waiting for Iain Ingram, to correct me and tell me surnames which once I knew but have forgotten.
The Inverscotia Singers made an album, I think around the time they performed on stv in the very early days of that station - MacGregor Kennedy kindly made me a copy in cassette form. No idea whether it is possible to find the vinyl, how many were produced / by whom -- perhaps Nigel Gatherer's site has info?

What info I have is from memory -- and my memory is cr*p!
So - the group went on expeditions most or every weekend, from when they were young - off to the hills and the bothies, maybe youth hostels? They learned and shared and sang songs of Scotland, of the hills - and I think they composed at least one or two? Some of them played moothies and they all sang, harmonised.
Once a month they would gather at Otago Street for a dinner, each bringing a dish for the table -- but no-one ever co-ordinated this so on occasion there would be too many soups and puddings and insufficient - or no - mains!
They were members of The Scottish Patriots Club(?) and met like-minded people with whom Scottish affairs/politics/history and culture were discussed.
The Inverscotias held an annual dinner which would be organised each year by a different pair of them; the guidelines were the venue had to be North of the Highland line (unless it was Tibbie Shiels Inn)be no more than a certain price for dinner bed and breakfast (£45.00 at the time of speaking to me)the bar to stay open till the last man went to bed (all night!!)and no women to be present after the meal served (chauvinist pigs that they were!!!)and - any man who did not respond to the dinner invitation would never be invited again - no excuses accepted!
Everyone knew to meet at the toilets at Anniesland Cross on the Saturday closest to 9th December at (oops I can't remember what time?)where that year's organisers would issue them with coded instructions - precursor to car treasure hunt! Individually they had to work out the route and the venue then make their way -- no following anyone else! Early arrivals would have their choice of rooms, and be established in the bar awaiting the stragglers. After the dinner a memorable evening of songs and drams and toast would continue into the wee sma' hoors.
As the years went by and other singers and musicians came to know the group invitations would be extended to a select few; so the dinner numbers grew to perhaps forty or fifty - with the proviso that if the invitation was not accepted, or on any future occasion the person did not attend - they would never be asked again!
The dress code for all events was kilts or tartan trews, I think even for hillwalking? As they got older, some began to use camper vans rather than tents, walked up the paths and ridges rather than climbing faces - - but their bothy culture and songs were always in their hearts.
An annual Tryst continues, organised by the 'younger' generation (many of whom are grey or white haired themselves!) and keeping the singing tradition alive. For a while there were still a few originals with them, but Jimmy was the last of them and he was no longer able to attend events in the last few years.
I think the 'tartan trews' pair would have been Jimmy Jennet and Jim Cameron? Perhaps Graham Irvive or Rab Collinson could confirm? I think Jim Cameron was one of the additions to the original group, he had dark hair and sang some Gaelic songs as well as Scottish -- and he had developed great skill as a hobby leather worker, made traditional pouch sporrans (capable of hauding a whisky flask) with a leather whangie that held it on rather than the modern buckled chain thing Jim also made beautiful kilt belts - his work was very distinctive, and he donated a sporran annually to the dinner -- not sure if they raffled it or awarded it?
At Jim's funeral the family invited volunteers to take on the leather craft tools and materials - and Tom Hill took up this offer, carries on the tradition.
Re Girvan connections - again Graham and Rab will know! Not sure if they look at Mudcat tho - -? - - -