Regarding the no traffic in Piccadilly, I had come across something about them closing the West end for Christmas shoppers. However it appears that this was not the case in 2013, it was abandoned for that year.

Traffic-free shopping day in London's West End scrapped

Published 11 October 2013

An annual traffic-free day for Christmas shoppers in the West End will not be held this year.

VIP (Very Important Pedestrians) Day began in 2005 and attracted one million people to Oxford and Regent Street in 2012, garnering sales of over £17m.

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In the past, the day has seen hundreds of buses re-routed and shops offer entertainment and relaxation zones.

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"All the people coming to central London and dancing in the middle of Oxford Street did not go out that day and spend enough money in the shops."

The NWEC said traffic would be redirected from Regent Street on 2 November for a motor show and then again days later when the Christmas lights are switched on.

Oxford Street will also be closed to traffic on 12 November when its Christmas lights are turned on

https://www.bbc.co.uk/news/uk-england-london-24499194