The view from Magdalen Bridge, Oxford, has been restored to its former glory just in time for May Morning

The view from Magdalen Bridge was spoilt for months as Magdalen College had to repair a crumbling wall in the River Cherwell below.

Machinery and big metal sheets crowded the riverbank as contractors fixed the problems caused by tunnelling tree roots and burrowing crayfish.

Now the college has finished the job just in time for thousands of revellers to crowd the bridge for May Morning on Monday.

New metal sheeting below the water level is now protecting the wall below Addison's Walk from further damage.

The problems caused by burrowing crayfish came to light last August when Magdalen College applied for planning permission to repair the partially-collapsed wall.

The collapse was blamed on signal crayfish – an invasive American species which has populated many of Britain's rivers – and the position of the wall on an outside bend of the river.

The college warned the bank was 'badly degraded' and could threaten the waterside walk – part of the Grade I-listed Water Meadow – if is not repaired.

Its planning application promised the works would 'sensitively reinstate and stabilise the bank and ensure these grounds continue to remain in use'.

College bursar Mark Blandford-Baker confirmed this week: "The work is finished and can be seen from the bridge.

"The crayfish were a contributing factor but the principal problems were deterioration of the wall and heave caused by the big tree we removed at the start of the works which was leaning to the river and might have fallen anyway – its root structure was causing the main damage behind the stonework.

"The new wall will last a very long time. We are going to replant flowers and shrubs in the right seasons."

The river bank will be planted with flowers and plants again in due course to bring this famous view of Oxford back to its former glory.

The signal crayfish, or Pacifastacus leniusculus, is described by the Environment Agency as a predator with a 'ferocious appetite'.

It feeds on fish, frogs and invertebrates, as well as plants, and even eats individuals of its own species.

In the winter it takes shelter by creating burrows in river banks that can be up to two metres deep, entering a kind of hibernation called 'torpor'.

An Environment Agency spokesman said it was 'unusual' for the crayfish to cause structural damage to walls along banks.