In 1967, a revolution began in Norwich when London Street became the first shopping street in the UK to be pedestrianised. 

The closure of the street to traffic was intended to make the city more accessible to walkers but that may now be in jeopardy as the paving slabs that line the popular shopping area appear to be sinking. 

Kelly Robinson, 31, of Norwich, was walking along the street on Friday when she noticed a dip and later felt pain in her knee.

The sinking slabsThe sinking slabs in London Street (Image: Submitted)  "I was walking along London Street, minding my own business after enjoying some lunch at the market when suddenly I lost balance," she said.

"After looking down at my feet I realised the pavement appeared to be collapsing in on itself.

READ MORE: Fire breaks out at tanning salon

"My knee has hurt since.

"I worry others may be at risk of peril, something needs to be done."

London Street is one of the busiest streets in NorwichLondon Street is one of the busiest streets in Norwich (Image: Submitted)

Photographs show that six pavement slabs have begun to sink, with several of the surrounding tiles also beginning to dip. 

One proposed theory is that the situation could be a result of subsidence or the beginning of a sinkhole. 

Norwich City Council has been contacted for comment.