Car = Scout with 17" rims.

 

Right, so, I picked up a flat and had to put the spare on. Replaced spare etc. Picked up a fullsize alloy an tyre. So the spare now becomes a spare spare.

 

However, I noticed that the spare spare is the same size and spec as the one on my dad's Elegance. Now, whilst on the Scout, it's a "space-saver" (NOT a pram-wheel!) but given it's the same spec as the Elegance, would the 50mph limit still apply?

No. (Provided the load/speed rating is the same and the wheel offset is correct).

Edited 27 June, 201510 yr by Metblackrat

The tyre/wheel needs to be the same size as the other 3 on the car for the 50mph limit not to apply.  Same size means diameter, width and profile (height - 45, 50, 55, etc.).