Listed below are the latest map release dates.
OS Explorer OS 1:25,000, OS 1:25,000 HD
and
OS Landranger OS 1:50,000, OS 1:50,000 HD
1st December 2018
1st September 2018
1st June 2018
1 March 2018
1 December 2018
OS Vector Map Local Colour
1st October 2018 - a full update as the OS has changed some small details in how the map is drawn.