I did go back 16 months (if you check the dates) unfortunately a typo shows it as 6 months. so, to correct:

Continuing to fall (overall) to make the pound show a better view of its true value.
The fall started well before the vote, even though all the pundits thought we would stay in the EU.
A re-balancing was overdue.
25/2/15 (16 months before vote) 1.3665
23/6/16 (day of vote) 1.305
31/10/17 (yesterday) 1.141
And yes, it's not exactly 16 months as rates aren't normally shown for 'non-trading-days'.