These are the dates for 2020.
5th April, 19th April, 16th May, 14th June, 28th June, 26th July, 9th August. 23rd August, 13th Sept, 27th Sept and 11th October
2nd May (limited availability) , 11th July. 5th Sept (sold out) and 3rd October
Tickets are on sale from December. Walking tour vouchers are on sale now.