Excellent work from the Freedom Association here. They've sent FOI requests to every local authority to find out what vaping rules they impose on their staff. Nearly all of them ban vaping indoors and a large number of them force vapers to stand in smoking shelters (at least they have smoking shelters, unlike the NHS).
No evidence is provided by any of the councils for the ban on indoor vaping; there is none. The tobacco precedent means that authorities think they can ban anything on a whim (see also: the EU ban on e-cigarette advertising).
Do read the report. It's terrifying how stupid and illiberal people are in local government.