HS2 should be built to suit this countries characteristics, geography and journey patterns - capacity constraints (especially around London,
Birmingham and Manchester) and loading gauge make a dedicated line both viable and neccesary.
Yes, but I'm looking for a model for this country. Take the Ruhr, for instance, an area of about 4,400 sq km with a population of 5,000,000. Now, that's twice the population of the West Midlands (if you include Coventry), but is also about twice the size, so the population density is similar. The settlement pattern is similar as well, a number of cities that have coalesced into one connurbation. Now, the only genuine Ruhr ICE station is Dortmund, but just down the road, there are three practically on top of each other, Duisburg, Dusseldorf and Cologne. Essen and Borchum could probably argue that they are served rather poorly by ICE, but that's a different debate. There is then a high-speed section that makes a dash up the Rhine to Frankfurt (through an area with a lower population, but they can also use the old route through Koblenz and Mainz). Then you have another connurbation, with a clump of stations at Frankfurt, Frankfurt Airport, Fulda and Mannheim on a sort of triangle, plus Wurzburg a bit further on, before another dash to Nuremburg, and another to Munich. Now, this clump-and-gap pattern is very like our country, say London, West Midlands, Greater Manchester, Mid-Lancashire, Carlisle (on its own) and the Central Belt separated by varying distances from 50 to 150 miles. It's the same on our side of the Pennines: London, Peterborough (which acts as a feeder from East Anglia), the West Riding, York, Teesside, Tyneside (Newcastle might cover both), Berwick and the Central Belt. France tends to have stand-alone cities with individual stations, plus the middle-of-nowhere regional stations.
Therefore, my idea for high-speed rail in Britain is the same dash-and-stop one as in Germany. Basically, you build new sections of fast line to link the existing stations, with some smaller ones bypassed to save time. Increasing the loading gauge is a different question, and I'm deliberately assuming Eurostar-sized trains (maybe even cascaded Eurostars) to keep costs down. It probably is possible to increase loading gauges at many of the older stations, but bridges present a problem - although some would have to go during electrificaiton anyway. Tunnels, I'm leaving alone, because most of them are on section where new line would be put in anyway.