My written evidence to the @HLConstitution Committee was published last month and is here: https://committees.parliament.uk/writtenevidence/16034/pdf/. I summarised these submissions in the below thread in November. https://twitter.com/Francis_Hoar/status/1329380025427243019

The position of the UK Government in 2011, in a section revealing entitled 'Business as Usual':

'The UK Government does not plan to close borders,stop mass gatherings or impose controls on public transport during *any* pandemic.
(Emphasis added)

( https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/213717/dh_131040.pdf, p 57)

Indeed, for two reasons in particular:
(a) The Publ Hlth Act is only envisaged as allowing regualtions to give local authorities powers to impose quarantine; & only for infected ppl; &
(b) The CCA is seen as the default means of imposing emergency powers. https://twitter.com/CoojeeBear/status/1347143223530151939?s=20