If someone had managed to bottle the essence of the 1960s – the exciting, adventurous bits – wouldn’t you want to take at least one deep draught? I certainly would. I sometimes long for the power to recreate that odd, dangerous, thrilling time, if only to see if I have got it right in my memory. In fact, they did bottle it. But nobody is allowed to taste the vintage. Well, almost nobody, as we shall see.
Source: Why is a brilliant BBC serial kept in its most secret vaults? | The Spectator