Taking a quick look at RTT typical fast line off peak departures from Euston are:
xx00 Manchester (first call Stoke on Trent)
xx03 Birmingham New Street (first call Rugby)
xx07 Liverpool (first call Stafford)
xx10 Chester (first call Milton Keynes)
xx15 Crewe (LNR 110 mph fast line to Ledburn Junction)
xx20 Manchester (first call Milton Keynes)
xx23 Birmingham (first call Watford)
xx30 Glasgow (first call Warrington)
xx40 Manchester (first call Crewe)
xx43 Edinburgh/Glasgow via West Midlands (first call Milton Keynes)
xx46 Crewe (LNR 110 mph fast line to Nuneaton, first call Milton Keynes)
xx49 Liverpool (LNR 110 mph fast line to Hanslope Junction, first call Milton Keynes)
Then add to this on some hours an XX36 Blackpool first call Rugby and the future 110 mph Grand Central Service to Blackpool at xx36 first call Milton Keynes.
This is impressive by anyone's standard, more services are run in the peak hours. I believe
@Bald Rick and
@ChiefPlanner have referred to the WCML timetable south of Rugby as a thing of beauty and I can see why (I look forward to reading more about it in their memoires!)
Anyone doubting the need for HS2 would do well to look at this and explain exactly how you would fit more trains onto the fast lines out of Euston.