"It was like a rock concert. The streets were lined with people. Literally there were people standing outside their windows, on ledges, on lamp posts all calling out," Guha said.
"I mean, no one had a clue who we were. People were shouting, 'Are you the WAGs?'
"We didn't care, we were just there for the party."
The huge crowds meant the buses took their time trawling through the streets of London towards Trafalgar Square, which meant more time to down champagnes.
Unfortunately for Guha – described by Howard as the "quintessential English rose" – that caused a problem for her bladder, forcing her to find a creative solution.
"This thing took ages. It was like, an hour, and we were obviously on the champagnes so we were just downing it and having the time of our lives and then it got to the point where my bladder was full and I desperately needed to go to the toilet," she said.
"I've since found out that Kevin Pietersen was able to stop the bus in front and pop out to go to (the toilet at) Starbucks but I wasn't afforded that luxury. I was told, 'You have to wait until we get to Trafalgar Square', which was another 20 or 30 minutes away.
"So I, at this point, had no other option but to go downstairs. There was no one around and I saw fit to find a cup to pee into and relieve myself so that I could carry on my drinking."
Howard added: "We started this show with me saying I sat next to you and your beautiful, refined voice and I was like, 'Wow, she is the quintessential English rose'. Now you're telling me you had a p*** in a cup on a bus, Isa Guha?"
To be fair, Guha and Howard's chat delved into a lot deeper issues than just urinating on a bus. They talked about her upbringing, moving from India to England, her career highlight of taking nine wickets in a Test against the Aussies in Bowral and the challenge of moving into broadcasting and how she has gone from an inexperienced novice behind the microphone to one of the most recognisable and sought-after commentators in world cricket.
Howard and Guha also talked at length about her admiration for her mum and the struggles the cricketer faced dealing with her death as she opened up about the toughest period of her life.
But there's always room in a conversation for toilet troubles on wheels.