Unlike other seasons when I've been able to find the "Advance Information booklet" which lists most of the tours for the seaon, I've only been able to find a few notes about the occasions that it ran in 1961. It would probably run with the same frequency as other years with 30 to 40 tours.
The table shows only the known tours:
These two scans are courtesy of John Paton. The first is not a public Six Lochs Land Cruise, but a "Garex" (Guaranteed Excursion) for the company Stewart and Lloyds Ltd, a steel tube manufacturer, from Coatbridge (depart 10:20, return 20:35) on Saturday 20 May. It was booked for 491 passengers to be carried on four Hamilton twin sets, reporting number 331. It did the clockwise Six Lochs circuit passing through Glasgow Central Low Level on the outward journey with a 1hr 20 min break at Crainlarch, 50 mins at Killin, and just over 2 1/2 hours at Callander.
The second is for a public Six Lochs Land Cruise the following day, Sunday 21st May. Booked for two triples Hamilton sets (likely 107s), the coaches were to be labelled A to F suggesting that the passengers had allocated seats on the train. It is noted as a "Halfex" (Halfday excursion), despite being just over 11 hours long from. Setting off from Cambuslang at 11:15 and carrying reporting number 332 it picked up at Rutherglen and Coatbridge then headed for the anti-clockwise Six Lochs circuit via Garqueen North Junction and Greenhill. Two hours were allowed for lunch at Callander, and just over two hours at Killin in the late afternoon. The train was booked for a return to Killin Junction in this layover - possibly to allow the Glasgow tour to traverse the branch. Just over an hour was allowed at Crainlarich, the return journey passed through Glasgow Low Level. When sending the scans John noted that the 1961 “Hours of Opening of Signal Boxes” shows that line being closed on Sundays, and assuming that there would be no ‘long-section’ working between Dunglass Junction and Rutherglen, a large number of boxes would require to be opened for a very short time. Drops offs were at Rutherglen, Cambusland and finally at Coatbridge at 22:26.
Photographer Sid Rickard captured the tours on two dates this year. His images are now with Cresselley Photos, where a pdf listing all of his photos can be downloaded.
Easter Monday (3 April) - his images of these tour were negatives AD25-9, and previews can be found on page seven of the Diesels and Misc 1 section:
23 July - his images of these tour were negatives AD54-6, and previews can be found on page seven of the Diesels and Misc 1 section:
Another photograph I've encountered is dated July 1961 and shows a Class 107, a two-car Met-Camm, and another unknown set crossing one of the bridges a few miles north of Callander in the Pass of Leny. This is in the book "BR Diesel Traction in Scotland" by George O'Hara on page 40. However in the WAC Smith image the unit carries a yellow panel so it must be from a later year.