The Royal Day Out is just a ticket to three sites w/i the B'ham Palace complex. Buckingham Palace, the Royal Mews and The Queen's Gallery. You can buy it ahead of time or after you are in London from any of the three ticket offices.

B'ham Palace does have timed tickets - but you don't have to book far ahead. You DID back when it first opened when it totally sold out. But can buy it ahead on-line -- or -- you can go to the ticket kiosk, buy the Day Out ticket w/ a set time later in the day for the State Rooms and then go to the Mews and Gallery.

When you wrote this did you mean "The Royal Day Out Ticket"?>

nope did not even know what that was until my friend janisj so kindly explained it - and i agree after witnessing lines just for the part of the palace that is only open to the 'rabble' in August and Sept or so it is easy to get in without much of a wait - and i also loved the Royal Stables - all the royal carriages and the huge horses - all authentically accompanied by the smell of horse manure - a working stables (open year-round as is the Queen's Art Gallery).