Change of use from public house to a public house with separate betting sho - Public forum - Planning Advisory Service (PAS)

I am after views on this query: Would planning permission be required to change the use of a large kitchen area in a public house to a betting office? The public house would be run independent of the betting shop and it would have a seperate access point from visitors. It would also have different opening hours and signage. I note that the Use Classes Order grants changes of use from pubs to betting offices but as I read it that would be either if that change of use included the entire building or the betting office use would only be an ancilliary use.