Here's an interesting anti-HS2 (but pro-rail) report by the National Economic Foundation (NEF).
https://neweconomics.org/2019/03/a-rail-network-for-everyone
Apparently it was commissioned by Friends of the Earth, which gives you some idea of the motivations behind it.
There's a summary in the Guardian, which is rather less thoughtful:
https://www.theguardian.com/uk-news...orth-midlands-london-new-economics-foundation
The main report has been written by people who know the gory detail of recent railway operation, economics and upgrade programmes (one of them is Paul Salveson).
Instead of HS2, it proposes a 10-year £22.4 billion programme of classic upgrades along all three main lines.
This includes multiple flyovers, four-tracking (eg Coventry-Birmingham), electrification of everything in sight (Holyhead anyone?) and reopening all the closed lines you could possibly want (eg Woodhead, Waverley, Colne-Skipton, Bangor-Caernarfon).
There is plenty of interesting meat, but I did enjoy the unfortunate mention of the upgrade of "Warrington Bank Key".
It says it will take 10 years, but to me it looks more like 50 years at Network Rail's usual pace (with all the planning and land purchase issues, not to mention technical challenges).
Examples of the WCML upgrade elements:
The main thrust is that the business case for HS2 does not add up, and that the regions are disadvantaged and need major local investment instead.