Detectives searching for missing Gaynor Lord have released new footage of what they say is the last sighting of her on CCTV before she disappeared.

The 34-second clip shows the 55-year-old, wearing glasses and a long coat, walking along St Augustines Street in Norwich, which is busy with passing traffic, at 4.01pm on Friday December 8.

Mother-of-three Ms Lord disappeared after leaving work early from Norwich city centre at 2.45pm. Her belongings were reported found in Wensum Park – around 1.5 miles away from her workplace at Jarrold department store – at around 8pm.

Norfolk Constabulary believes “it is likely” Ms Lord may have entered the River Wensum after her clothing, mobile phone, glasses and jewellery, including two rings, were discovered at various locations in the park.

Her coat was discovered in the river, which runs through the park.

A huge search is ongoing by specialist divers, who the force said are working in an “extraordinarily challenging environment”.

Speaking to media at the scene, Chief Superintendent Dave Buckley said it will take “a couple of days” or longer to complete the search of the stretch of river.

“We’re putting sonar equipment across the river, which is quite detailed in allowing us to try and target divers to where we think there might be objects,” he said.

“But equally, it’s very, very challenging. The river is very, very full of water with all the rain, full of lots of debris. The divers can see about one foot in front of them.

“So it’s an extraordinarily challenging environment for them to work in so it’s slow, methodical at the moment, working with equipment and it will take probably a couple of days to get to a position where we’re kind of content with what we’ve done. It may even be longer.”

Mr Buckley said the force was keeping an open mind about what happened to Ms Lord but “everything we know is pointing to a high probably that Gaynor went into the water”.

But the senior officer said: “Nobody’s seen her go into the river, nobody’s seen her go into the water. But we know she ended up in the park.

“At the moment there’s nothing else the CCTV is showing about who she may have spoken to, any interactions she might have had.”

Mr Buckley was asked if detectives had worked out why Ms Lord left work early and he said they had not.

He said: “Some of this behaviour is out of character.

“We can’t explain some of her behaviour that day.

“We’re working really closely with family, with friends, with anybody else who might have had contact with her in the recent days or weeks to try and understand why this might have happened.”

He said officers are supporting her family, adding: “People are very shocked by what’s happened. Nobody knows why she’s done what she’s done.”

Mr Buckley also confirmed his team has consulted with officers from Lancashire Police who worked on the search for Nicola Bulley.

Ms Bulley’s body was found in the River Wyre on February 19, about a mile from where she vanished while walking her dog in St Michael’s on Wyre on January 27.

The Lancashire force was criticised over its handling of that investigation and the disclosure of Ms Bulley’s personal information.

Mr Buckley said any lessons learned from that inquiry will be incorporated into the search for Ms Lord “which remains a missing persons inquiry”.

The CCTV footage released earlier this week shows Ms Lord jogging up the cobbled Bedford Street after leaving work at the Bullards Gin counter in Jarrolds department store at 2.45pm, more than an hour before her shift was due to end at 4pm.

She was wearing a white shirt and a yellow tank top, and was carrying her large olive-coloured coat beneath her arm.

She can be seen on the footage walking on to London Street at 2.47pm and then crossing the road on Queen Street without waiting for a red light, narrowly missing moving traffic, heading towards the cathedral.

Around 30 minutes later, at 3.22pm, video shows Ms Lord putting her jacket on as she walks away from Norwich Cathedral.

At 3.49pm, CCTV captured her walking along St George’s Street near to the Playhouse theatre.

She then walked along St Crispins Road towards Pitt Street at 3.53pm.

She was last sighted by CCTV on St Augustines Street at 4.01pm, police said.

Ms Lord is described as white, 5ft 6in, and has a blonde shoulder-length bob.