Thanks to the co-operation of the Class 40 Preservation Society and EWS, our cameras and microphones were on board the loco to capture the Class 40 as it tackled the challenging gradients of two impressive routes.
The cab footage is complimented by lineside views of the train as it heads for Kyle where it became the first Whistler to reach this remote Scottish outpost in 24 years
DISC 1: Aberdeen-Inverness features 40 145 on the 108-mile route from Aberdeen to Inverness. It begins with the 32-mile climb through Dyce, Inverurie and Insch to Kennethmont summit.
After dropping through Huntly the line climbs again through Keith to run through the heart of 'whisky country' to Tauchers summit.
After descending to Elgin, a series of varying gradients carry the line through Forres and Nairn to Inverness.
With all but five miles of the route single track, and with all but one of the stations still equipped with semaphore signalling, this line still retains much of its charm from when Class 40s regularly plied the route.
DISC 2: Inverness - Kyle of Lochalsh. After setting off from Inverness and crossing Clachnaharry swing bridge, 40 145 is at full bore as it powers alongside the Beauly Firth towards Muir of Ord.
After a spirited run to Dingwall, the train leaves the Far North Line to take the 63-mile branch to Kyle. And that's where the serious stuff begins.
The four miles of 1 in 50 up to Raven Rock summit have the 40 slipping on a wet rail.
The 1 in 50 climb from Garve to Corriemoillie summit is equally loud, as is the 15-mile slog from Lochluichart to Luib summit.
The last 18 miles are truly picturesque as 40 145 whistles its way along the shores of Loch Karron before arriving at Kyle.