IIRC the limit according to the standard is £100,000/day but most banks impose their own arbitrary limit. Assuming things haven't changed in 5 years, this[1] lists the limits for a lot of banks. I can also add to the list that Monzo's is £10,000/day.
1. https://www.moneysavingexpert.com/news/2014/11/customers-bei...