In one of the articles, it states, "In London, reservations of 90 days or more are not considered short-term stays per the 2015 Deregulation Act, and will not count towards your short-term limit."
So anything less than 90 days is considered short-term for London which means you can only have 90 days in total from January 1 to December 31 from what I understand. You can do sort term and then try to get longer term guests on the Airbnb platform as you are not limited there.
David
Superhost Ambassador ~ Host Club Community Leader ~ Experienced Co-Host