What sudden drop ? Sterling was worth a bit less than €1.20 from 2008 until 2014, between 2014 and 2016 it was much stronger, since 2016 it has been worth a bit less than €1.20.
I have no idea what the value of sterling will be in the future, but all that happened in 2016 was that a brief (2 year) period of high valuation against the Euro was reversed.
Between the launch of the Euro in 1999 and 2007 sterling was worth over €1.40 it fell in 2007/2008 to €1.20 and except for the 2 year period mentioned it has stayed there since.