A lovely example of British Rail’s house style of the 1960s and 70s, now residing at the East Anglian Railway Museum. This map is from between 1965 (the introduction of the “double-arrow” British Rail identity), and 1978 (when the “Eastern” component of the logo changed from sitting in an outlined box to a solid box like the British Rail text). Can anyone date it more definitively?

Source: Deptford Draylons/Flickr