it's all a bit 'snakey' isn't it? no wonder BI had put that cartoon 'on the timer system' as a clue to the following...

 

oh and there's more...having found that 'cocktail holder' device in an office at st Helena's hospice...the marines were to code it out...something around the 'din' as in sound levels...along with the DNS....to then put the following upon the timer system...something around aircraft...."light aircraft" replies MI5 ONLINE...rather than by boat?...and seeing as there probably isn't anywhere to land...let me scan for more information..."a drop" according to maria...go figure:

 

https://en.wikipedia.org/wiki/EPNdB