So I called in some reinforcements in the form of the ever informative Snaik, and here’s what he told me:-
It’s not on any database on UK Defences, but a Pillbox on the North side could only mean they expected an attack from that direction as the Law would have been a strategic spot, for the Germans to use for their artillery spotters.
The bunker was built by the Polish Army in Exile, whose task was to defend the east coast of Scotland. They built all the Stop Lines and Coastal and Inland Defences, and a lot of them stayed after the war.
The Headquarters were at Bridge of Earn, the Polish Engineers Battalion at Dundee, and the Polish Reconnaissance Battalion at Perth. The Polish 1st 2nd and 3rd Rifle Battalions were at Tentsmuir, Cupar and St Andrews respectively. Numerous other companies of the Polish army were stationed throughout Tayside and Fife.
Other theories as to why the pillbox was situated there include to provide support to RAF Tealing which opened in 1942 as a pilot training station 3.7 miles due north. (See GC45JWC for more info), or to protect the covered reservoir directly in front of it on Law Crescent, which provided the water for three district heating systems encompassing around 400 homes.
If you want to find out more about this type of pillbox, here’s the linky:-type 24 pillboxes
As a wee bonus, here's a photo of the Dundee Home Guard. Can you spot Snaik's Dad, who during the war, lived on the Hulltoon(Hilltown). Unfortunately Snaik has no further information about what he did whilst in the Home Guard, as like many others, it was something he didn't talk about.
Now for the multi bit:-
The final is at N56 28.2AB W2 59.4YZ
A = number of sides the pillbox has, less the number of open gun slots.
B = the number of blocked up gun slots.
If the Pillbox has a pitched roof Y = 6
If the Pillbox has no roof Y = 1
If the Pillbox has a flat roof Y = 9
Face the front of the pillbox (ie face south) If the large tree to the left of the pillbox is a horse chestnut Z = 6
If the large tree to the left of the pillbox is a silver birch Z = 1
If the large tree to the left of the pillbox is a beech Z = 9