"The reception freaked me out," Anna confessed. "We had no idea, we didn't have a clue what was going on. We thought there might be four or five people watching!"
Channel 4 executives revealed the unofficial viewing figures at a press conference for series winner Craig Phillips and runners-up Anna Nolan and Darren Ramsey.
The average audience was nine million, but at its peak, the show attracted a 56% share of all people watching television. The figures were Channel 4's best ever for a Friday evening and the highest this year.
During the press conference, Craig admitted he was looking forward to watching videos of the programme, while Anna said she wanted to "sleep for a week".
The last three contestants spent 64 days shut inside the purpose-built house in London's East End, as millions watched their every move on the internet and television.
Bemused
The trio appeared a little bemused by all the press attention and were astounded by the success of the show.
"The reception freaked me out," Anna confessed. "We had no idea, we didn't have a clue what was going on. We thought there might be four or five people watching!"
She added: "We were completely overwhelmed by the crowd who had gathered to welcome us and stayed there in the pouring rain."
Father-of-three Darren, 23, said: "I didn't realise the scale of this - I'm just taking a step back and want to resume reality...spending time with my kids and get some peace of mind."
Craig, who donated his £70,000 prize money to teenage friend Jo Harris, to help pay for a heart and lung operation, admitted: "I don't know why I won - you'll have to ask all those people that voted for me."
"I need the press and the public to help me....she is a unique young lady and it is wonderful to be in the position to help her."
Internet holiday company ebookers.com offered to cash in its offer to Craig of a trip to Mount Everest - worth £3,000 - to put towards Jo's operation.
Craig, 28, would not be drawn on whether he had any plans to pop the question to long-term girlfriend Shelly, answering "no comment", before adding: "She's a beautiful lady, I'm sure many men would like to marry her."
He said he was looking forward to watching videos and reading press reports about Big Brother.
"I'd be interested to see what has gone on...I spent a long time wondering what was going on outside."
Skateboard
Anna, 29, who was reunited with girlfriend Tanya Paice, said she was considering going back to her job working for a skateboard company, but revealed she was considering other options.
The former nun, who was awarded a two-week holiday in the Caribbean as a consolation prize, said: "People have been suggesting different career paths I can take - I'll have to decide which ones I fancy."
Darren made it clear he would not be resuming his post at the Millennium Dome. "Since I've been out I've heard some bad press about it!" he joked.
All three agreed they would never repeat their Big Brother experience, but the show is almost certain to go on without them.
Channel 4's commissioning editor Liz Warner admitted: "We'd be foolish not to go for a second series, although we haven't committed yet."