Well does having platforms impact line speeds?
I ask because on my travels, I’ve seen a 90mph for the Up Fast just south of Platform 4 at Luton - could this not be raised to 100mph or 110mph?
That’s only be example, the only other methods of raising line speeds is remodelling Leicester and it’s approaches/Bedford.
The 90 south of Luton is because of the curve between there and Parkway. Rather difficult to deal without landtake and some expensive civil engineering. Not worth it for a few seconds. Leicester has been / is being dealt with within the main physical constraints, and as everything stops there doing anything more would be a waste of effort.