50m. This is the description from the Old Leicestershire Climbs Book from the early 90's
Baptism 40m VS 5b at high level . ***
4c for the low-level variant. E3 for non-swimmers
From the bay walk around the grass bank. Up this and traverse the undercut slab to its left-hand end. Move down across a steep wall to a hard move into a dirty corner lapped by overhangs. There is an old peg here.
Traverse down across a wall to the left and continue the traverse at water level enjoying the transformation from sound rock to loose vegetated choss.
D.T. Holyoak and P.J. Howard, Oct 1970.
4c low-level variant: if the water is low (and you have long legs) it is possible to make a giant stride and pull across underneath the initial overhang and continue to complete the first section.
On the second section swing down the borehole on the right and traverse left centimeters above the water. Rejoin the main traverse. Impossible at high water.