@Sir Felix Pole - Thanks for that and the link to the newsreel.
From the newspaper indexes the train ran overnight from London to Bolton Abbey via Northampton Leicester and Hunslet (Leeds). Then it took them to Colne. At some point they spent a night at Lowton Junction.
Yes I saw some of these articles, apparently it stopped at Leicester for seven minutes.
Since I posted this topic I've found out a little more... King George VI and the Queen left London at 11.55 pm, booked to arrive at Bolton Abbey station after 4.30 am. It arrived at 4.42 am and was placed in a siding there.
At 9.25 am the train left Bolton Abbey and arrived at Colne 10.00 am and the Royal party started their tour by car. Rose grove driver Mr. W. Spencer drove the pilot engine of the Royal train from Colne to Fleetwood where the Royals would re-join the train at 5pm.
Now, the question is - Did Mr. Spencer go down the main line through Accrington, or via the loop line (Padiham and Gt. Harwood to Blackburn instead)? Well, I've looked at the passenger 1938 time table and this is what I found - There is a two hour gap in traffic between 10.55 am and 12.55 on the loop line. Generally, all local goods trains travelled the loop early in the morning and in the evening.
Now let's take it from Accrington - During that two hour period, it's quiet until you get to busy old Accrington. Here there are no such gaps in traffic heading west, which leads me to conclude any route planner looking at running the Royal train that day from Colne must surely have chosen to divert the train away from Accrington? And that means using the loop line...
Here's what I think happened time wise. The King and Queen arrive at Colne 10am, lets say by 10.05am the train is moved to one of three carriage shed sidings. The Royals had slept on the train overnight from London, and would have had breakfast on it before arriving at Colne. In short, this train now needs a good old clean. Lets say 1.5 to 2 hours for that. This now (after cleaning) puts us bang on for that clear two hour period to route the now clean Royal train via the loop line. I've always said, my maxim is to write about the true actual facts about the loop line. I don't want to take 2 + 2 and make 5, I just can't prove it went ECS via the loop that's all.
Trial Runs:- The following both surprised me and yet didn't... Back in 1912 during King George V's reign, senior members of the L&NW and the L&Y had a practice run from Wigan NW to Colne and back with the Royal train no less. This was done late November / early December 1912 ahead of the King's tour the next year. I wonder how many other trial runs were performed over the years around the country?
As for how many branch lines saw Royal trains go along them, I would have thought there would be quite a few, however in the context of how many branch lines there were back in the day, the ones that did see Royal trains would be a select minority?