In February three fire engines and around 20 firefighters rushed to the blaze at Anna’s home in Ilford, London, at 10.20pm.
Despite their best efforts, Anna died at the scene.
Her agent Shane Collins, who also represented her best friend Barbara Windsor, said: “It is very sad news.
“But I’m happy that Anna will now be with her best mate Barbara and her beloved husband Terry Duggan.
“Anna was a great lady and a really nice person. She was a fantastic client to look after. I can’t tell you how much I liked her.
“She went through a hard time after she broke her hip a few years ago but came back to work again and appeared in EastEnders with a stick.
“Over the last couple of years she has been at home with friends popping by and her neighbours looking out for her.”
Tributes were paid to the actress with Cheryl Baker, singer in 80s pop band Bucks Fizz, saying: “I have just heard the awful news that my fabulous mate, Anna Karen has died in a house fire.
“What an horrific way to die, I can’t bear to think about it. I adored her – She was an absolute treasure, both on and off the screen.”
‘SMOKE AND FLAMES’
Sivalai Pavananthakumar, 33, said neighbours raised the alarm after smoke was seen pluming from her front door.
He told The Sun: “There was a lot of smoke, and flames, people in the street had seen what was happening and came out to try and help.
“The fire brigade and police were here quickly and kicked down the door, there was so much smoke.”
He added: “I recognised her and would see her everyday when I took my children to school, she was a nice old lady and always said hello.”
Another neighbour added: “I knew her from EastEnders, it was like having a celebrity living in the street, she was a lovely old lady and always spoke to everyone.”
A third said: “She was an icon when she was On The Buses, everyone would have recognised her, but not so much as she got older.”
London Fire Brigade are now probing the cause of the blaze, which damaged the ground floor of the mid-terrace property.
The fire was under control by 11.38pm, the force added.
British-South African actress Anna was On the Bus’s last surviving cast member after it ran for seven series from 1969 to 1973.
Anna – who was married to actor Terry Duggan before his death in 2008 – was best known for her role as Olive in On the Buses, featuring in all 74 episodes of the hit sitcom.
She also appeared in the series’ spin off films, On the Buses – the highest-grossing film of 1971 – Mutiny on the Buses and Holiday on the Buses.
Anna became close friends with legendary actress Barbara Windsor after the pair both featured in hit classic Carry On Camping in 1969.
The pair reunited in 1996 when they both had recurring roles in EastEnders.
Karen played Aunt Sal, the sister of Windsor’s Peggy Mitchell, who would appear for one or two episodes at a time.
Windsor died on 10 December 2020 aged 83 and left £1,000 in her will to Anna.