The star of EastEnders and the Carry On films died in December aged 83 following a six-year battle with Alzheimer's disease, and her funeral on 8 January took place with limited guests due to coronavirus restrictions.
Biggins, 72, told The Sun: “It was an extremely sad day. There were just 29 of us there because that morning one of the guests got COVID, can you believe it?
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“To play to 29 people who were sad and upset, it was very difficult to get the odd laugh here and there. And of course, you had to have a laugh because Barbara was a funny woman.
“Most of my memories are of having a great laugh with her. That is what she was about so it was really terribly sad.
“Sadly I think this is going to go on until 2023 before we go back to complete normality but let’s hope that at the end of this year or the beginning of 2022 we really can send her off in a big way.”
“Normally we could have filled Wembley Stadium with people who would have wanted to say goodbye. The streets would have been lined.”
Watch: Dame Barbara Windsor’s funeral takes place amid COVID-19 restrictions
Dame Barbara’s funeral was attended by her widower Scott Mitchell and celebrity friends including David Walliams, Matt Lucas and Ross Kemp, who played her on-screen son Grant Mitchell in Eastenders.
The ceremony at Golders Green Crematorium in north London was also attended by journalist and Loose Women panellist Jane Moore, as well as other EastEnders actors including Dean Gaffney and Jamie Borthwick.
Under the current COVID-19 rules, no more than 30 people are able to attend a funeral in England, masks must be worn and singing is limited.
Dame Barbara was best known for her performance as Queen Vic landlady Peggy Mitchell in EastEnders between 1994 and 2016. The actor had previously found fame in the Carry On movies and had a long panto career, often working alongside 72-year-old Biggins.
Dame Barbara and husband Mitchell worked with Alzheimer’s Research UK to raise funds and awareness of the condition after she went public with her diagnosis in 2018.
Mitchell recently said he has been “overwhelmed” by generous donations from fans to fund Alzheimer’s disease research after he set up a JustGiving page to honour her memory.
Over £159,000 of charity fundraising has been made in tribute to his late wife, who was diagnosed with Alzheimer’s disease in 2014.