I'd be interested to know how much is walkable.
It is about 7 miles from Lutterworth to Cosby - it took me 7 hours to walk due to the hideous amount of overgrowth.
A summary of the current condition of the stretch starting from bridge 426 which went over the former A427 (now A4303):
Bridge 426:
One of the first bridges to be demoilshed - sometime before 1977. The southern abutment was visble until 1999 when it was removed when the A4303 was widended as part of the Lutterworth Southern bypass. The northern abutment was removed at the same and had been hidden by earth. The cutting on the south side has a platelayer's hut which is visible from the road. The embankment on the north side is accessible and is a footpath up to the station. The southern half of it is now owned by the county council, the northern half still being private unregistered land. Bridge 426 was one of just three single arch brick bridges over a road on the London extension, the others being at Whetstone and Basford.
Bridge 425:
Extant, single arch bridge over River Soar, again fairly rare. The embankment is protected by Harborough District council as it provides a barrier between the town and the M1.
Bridge 424:
Steel occupation underbridge over the footpath to Misterton. Easiest access point. Eastern parapet collapsed a decade ago
Bridge 423:
Station access bridge. Extant but in very poor condition. Mud below never dries out. Head under it to access a footpath to the back of the station where the brickwork retaining wall for the upside cattle dock survives. Station Master's house survives. Short section of platform exists on the bridge.
Station site:
Covered by houses on Farringdon Avenue and Marylebone drive and the Uponor factory. My brother's friend at school lived in the house that has the station subway buried in the garden. Iron railings survive on eastern perimeter by the footpath
Bridge 422:
Gilmorton Road. Extant but small section of parapet removed. Trackbed north of here is a car park for the factories on the adjacent industrial estate which was served by the railway on a single siding.
Beyond the car park a small section of trackbed survives before it is occupied by a chemical manufacturer storing bottles of sulphuric acid etc. Afterwards, the countryside is reach and a short well preserved section of trackbed survives with a plate layer's hut. A number of fence posts survive and a tiny section of the wire. For the next 1.5 ish miles, the tracked is ploughed into fields.
Bridge 421:
Demolished. Carried now closed footpath. Location can be spotted from the M1 by the change in the motorway fencing.
Bridge 420:
Carried a single track road towards Gilmorton. Eastern abutment survives but rest demolished. For a short section north of here, the eastern cutting side survies as part of the M1 cutting side. but the rest is ploughed into fields. I found an AS1 chair here. The formation finally returns but is heavily overgrown.
Bridge 419:
Overbridge. Survives minus parapets. Served now closed footpath. Not at all visible from M1.
Bridge 418:
Ashby Parva to Gilmorton road. Filled in and parapets removed bar eastern pillars where the M1 bridge is bolted to it.
Bridge 417:
Carried only road into Cotes-de-Val. Was fully extant until 2000. I believe it was filled with parapets removed as one of the beams was visible in the road.
Bridge 416:
Steel underbridge, survives. Trackbed has a lot of mature trees growing at this point
Bridge 415:
Brick single arch underbridge over farm occupation crossing, survives.
The cutting north of here is largely vegetation free and there is a platelayer's hut. The cutting leads to..
Structure 414:
Dunton Bassett/Ashby tunnel (officially the later but always known as the former). Blocked by steelwork both ends - had to clamber up and back down again.
From the tunnel to Ashby Magna station, the trackbed is clear of vegetation but is owned by Coltman Bros timber ltd. Two small warehouses on site. Cattle dock survives as did some of the brickwork of the platform but this may have been removed recently.
Bridge 413:
Station access bridge. Survives but filled in and southern parapet removed (which led to platform). Station Master's house survives and the garden is extended onto the trackbed (north of bridge).
Part 2 tomorrow...