To perhaps explain a bit further, the railway has a concept of "permitted routes". In other words, the range of routes that it allows you to take between any two stations.
If your ticket is routed "Any Permitted" then this simply means you can use any of the above routes. It doesn't mean that you can use any random route you like, and indeed there are quite a lot of reasonable routes that aren't permitted.
For Manchester to Stevenage the permitted routes are:
- All the Manchester to London permitted routes, e.g. via the West Coast Main Line (including detours via Warrington/ Birmingham/Northampton etc.) to Euston. Or via the Chiltern route to Marylebone, or via Reading to Paddington.
- Then between the relevant London Terminals on the Underground, Thameslink or Elizabeth line via any "reasonable route"
- All the London to Stevenage permitted routes, e.g. St Pancras, Kings Cross or Moorgate to Stevenage via Welwyn or Hertford
- Alternatively, several routes that avoid London, e.g.
- via Sheffield, the East Midlands (Nottingham/Leicester/Derby) and Peterborough
- via the WCML, Nuneaton, Leicester and Peterborough
- via the Calder Valley or Huddersfield to York/Leeds/Doncaster and then down the ECML and its branches
- via Sheffield, Doncaster and the ECML
- via Crewe/Stoke, Derby, Leicester/Nottingham and Peterborough
So you have quite a broad range of routes to choose between.