On 7th June 2019, the Government announced its decision to change the 2020 May Bank Holiday from Monday 4 May to Friday 8 May.
Calendar makers are angry at a Government that gave them only 11 months notice, because they have already sent the 2020 calendars to print.
The final note to the Government Press Release states that a bank holiday is achieved by Royal Proclamation. Looking at the Gazette, the only recent Royal Proclamation that I can see on the matter of Bank Holidays is that of 24th May 2019 referring to bank holidays in Scotland.
Perhaps Her Majesty has not yet made the offending proclamation, and if so, then perhaps there is mileage in appealing the decision to the Crown.
Ah well, now I see that on the 10 July, the Queen has made the proclamation and it is published in the Gazette on 12 July.