It was meant to be a dramatic gesture to celebrate the Wensum and its place in the history and culture of Norwich.

But plans to award the river the Freedom of the City (FOTC) have hit troubled waters.

Green city councillors had tabled a motion to bestow the honorary title - previously awarded to sports stars, playwrights and artists - on the waterway at a recent City Hall meeting.

The ruling Labour party agreed to investigate the suggestion but has now vetoed the policy - after being told by council officials that "natural assets" were not eligible for the award.

The original proposal raised some eyebrows when it was tabled in January, with some online criticism suggesting it was a waste of the council's time.

But Lucy Galvin, the leader of the Green Party at City Hall, defended the idea and said the scheme had had "enormous support" with hundreds of people contacting her about it.

"It's a huge symbolic gesture that is very important for the city and its heritage so people can understand how important the river is," she said.

"If we can give the FOTC to Aviva, Norwich City Football and RAF Marham we should be able to support the river."

She denied the proposal was an example of 'virtue signalling'.

"You could say that giving the Freedom to anyone [is virtue signalling]. If you want to call recognition of something 'virtue signalling' then it is signalling the virtue of the river. Recognition of virtue is what the FOTC does."

Ms Galvin had originally called for the honour as a means of highlighting the importance of the waterway, which was once at the heart of Norwich life, and as part of wider calls to enhance and protect its biodiversity.

She stressed that it was not just the river she had proposed be given the honour but organisations that support it, such as the Norfolk Rivers Trust.

Announcing that the policy could not go ahead, at a meeting on Tuesday, Alan Waters, the council leader, said: “Unfortunately, as was suspected at the time, Freedoms can only be granted to people or persons, which would include organisations, but not to natural assets."

It is understood that no council money was spent investigating the proposal.

Mr Waters said the council was also providing ongoing support for the River Wensum Strategy - a city council-led partnership that includes the Broads Authority, Norfolk County Council and the Environment Agency.

At the same meeting, the authority decided it would grant the FOTC to the people of two Ukrainian cities, in a show of support for the war-torn country.

What's so important about the River Wensum?

In its upper stretches, the River Wensum is a chalk stream, which are globally rarer than rainforests, and is home to more than 100 species of plants.

A tributary of the River Yare, the Wensum is the principal river Norwich was founded upon.

For hundreds of years, the waterway was key to Norwich's industry, used for transporting goods and trade.

It has been listed as a site of special scientific interest and special area of conservation - two of the highest designations available in the UK.

Species that call the river home include the Desmoulin’s whorl snail, white-clawed crayfish, brook lamprey, and bullhead.

Rivers, including the Wensum, have been faced with growing pressures from sewage, agricultural pollution and invasive species.

The white-clawed crayfish is believed to be extinct locally due to a plague spread by non-native American crayfish.