A couple of years ago people were looking at increasing the non-EPS speeds on the WCML - with no 125mph non-tilt stock in use there hasn't been any reason to until recently. Have any of these changes been implemented on the track yet?
No, none.
Is there any hope for non tilting trains that can go the faster speed in a decade or two?
In some places, yes. soon in fact - south of Weaver Jn.
Is there actually an outline plan for a proper HSR to the Central Belt? How much time would it save - based on a distance of c 400 miles, (well) under 3 hours should presumably be possible, presumably?
There was a study about 10 years ago that I was involved in. 3hr is possible with bypassing of quite a lot of the existing route and HSR all the way would do considerably better.
The first study I was involved in had a 2h30 time London - Central belt. It’s definitely possible, and doesn’t need much in the way of tunnels from an engineering perspective, but is likely to through environmental choice. Environmentally, the difficult part is construction - as we are seeing now the construction period takes up a lot of land, but much of it is restored on completion and within a few years is back to nature.
It’s reasonable to assume that if we had the French Government in charge we would have a high speed line to Scotland by now. If you can put an LGV down the Rhône Valley, or through the Pyrenees, or (soon) down the Maurienne valley, then you can definitely do one on the edge of the Lake District and across Scottish moorland.
Whilst there is little chance of Government proposing this anytime soon, I do wonder if Scotland might steal a march and do something at their end. An HS ‘Tartan’ for 60miles from Gretna to Carstairs-ish would knock 17 minutes off the Carlisle to Glasgow / Edinburgh time, and also release a load of freight capacity. Should be doable for under £10bn (current prices).