I designed a cobbled madness stage in West Yorkshire as part of my Tour of Britain in the Race Design Thread
here which is about as brutal as possible; even with only half those obstacles you could have a good race. The alternative I thought would be to have a Manchester variation on the Ride London format, riding out to a circuit including Swiss Hill and then returning to the city.
Britain is a country which is full of untapped Classics potential. And at the moment cycling is in vogue and the fans would absolutely turn out in their droves if they marketed it right and got a useful crowd to it (the Velothon Wales, unfortunately, did not do so - many of us on the forum had no idea it was even going on, and the field drawn was decidedly average). But placing it in the middle of the spring season may not be ideal as the calendar is already relatively crowded there with established warmup races, and placing it after the main star attraction events would only lead to weakened fields with many top classics stars resting up. An ideal would be maybe a Trittico Lombarda type group of races clustered around the Ride London race, shoring up the field at the .HC and .1 level (I think the Ride London race benefits from being .HC as the mix of teams with motivated national and ProConti teams who've not done the Tour and/or are building up to their autumn peaks alongside some big guns and new stagiares wanting to showcase themselves has resulted in much better racing than we would likely see from the same parcours at the WT level) and allowing the races to piggyback one another for advertising and audience (especially as they can promote the races in the Tour de France coverage for a month prior to the races, ensuring maximum potential audience).
The other thing is that the Tour of Britain, I've maintained for a while, being located in September which in most years backs onto the Worlds (not this year of course due to a) Qatar and b) accommodating the Olympics), is in a perfect position to make itself the stage race par excellence for the Classics man. There is the possibility in Britain to make brutal cobbled stages (like mine above), saw-toothed Ardennes-alike stages, mid-length climbs but not MTFs a la Lombardia in the Lake District or Wales (in theory also in Scotland, but the race doesn't often go into the less populated but terrain-wise more interesting parts of that part of the UK), some punishing long and windy stages, and the six-man teams make it hard to control, but it wouldn't have to get repetitive. Given the nature of most Worlds courses, it could provide a very genuine tune-up opportunity for almost any type of Worlds, which can ensure a good field. A single day race could always look to break away from that, or to ape a particularly successful stage in the race so that popular run-ins can remain on the calendar without hampering the possibilities for the Tour of Britain, much like the Spanish races often had their appended events (the Subida al Naranco one-day race before the Vuelta a Asturias, or the Klasika Primavera Amorebieta a day after País Vasco finishes).