Venues 116 Pall Mall 116 Pall Mall, St. James's, London, 250 CapacityView Venue Ashridge House Ashridge, Berkhamsted Hertfordshire HP4 1NS, 350 CapacityView Venue Botleys Mansion Stonehill Rd, Lyne, Chertsey KT16 0AP, 500 CapacityView Venue Cain Manor Churt Rd, Headley Down, Bordon GU35 8SR, 123-170 CapacityView Venue Chelsea Harbour Hotel chelsea harbour, London, sw10 0xg Grand Ballroom: 500 CapacityView Venue COURTYARD BY MARRIOTT 1 Nobel Dr, Harlington, Hayes, 600 CapacityView Venue