A lady I talked to, yesterday, told me she used to help keep the culverts and ditches clear a long time ago. She doesn't remember a culvert under the road at 'The Lake'. Unfortunately. It's 'always' been subject to flooding there.
On the west side around that part of the lane is a field that has already been planted (not sure what with) but digging in there wouldn't go down too well. A cross section across the lane from west to east would be:
1) Planted field
2) Field margin about 1 to 2m wide - possibly a conservation strip we would not want to disturb
3) Barbed wire fence
4) Hedge
5) A drop of about 1m to the road surface
6) Road surface
7) A short rise of (less than 1m) which, years ago, had drainage grips which drained into
A ditch parallel to the road and currently full of years of brambles, hedge trimmings and silt
9) Another hedge
10) More fields (currently grassed with no livestock but may contain a dairy herd next year)
Another ditch (full of brambles, detritus and silt) and roughly perpendicular to the lane, runs down to a brook.
Water/drainage flow is west to east.
IMO the ditch parallel to the lane is, really, on the wrong side. It should be on the west side. I don't see us being able to change that. A qualified drainage specialist might have a better chance of convincing the 'committee' but we don't have one of those yet.
My plan would be to continue improving the ditches on the east side where, if there is a culvert under the lane, we should find the outlet. If we find an outlet that would give us more evidence to support a search for its inlet on the west side and significantly narrow down the search. A very large oak tree on the west side has (likely) destroyed the culvert if there ever was one there.
If we decide to move the ditch to the west side (and the lane to the east) we would need to put at least one culvert underneath the lane to give water in the new (west) ditch somewhere to go.
It would be nice to sort out the drainage at this particular point for, at least, the next 20 years.