Thank you for the advice @gr5! I will give it a go and report back.
I tried using a higher temperature before and the extrusion was better - I went up to 225C but then the nozzle would smoke before the print started. The prints came out darker in colour too so the filament was burning (see pics below). I am also not sure what effect that higher temperature has on the properties of the filament and if it releases any nasty fumes - the recommended temperature for Willowflex is between 175-185C.
Left print: darker printed at 225C , right print: lighter printed at 185C
I actually cleaned the nozzle using the Atomic method between Print 1 and Print 2 - because I thought Print 1 was underextruding - which turned out to be nothing compared to the underextrusion that followed! I will check for obstacles, maybe something got caught during the cleaning process - because the filament is flexible, the end was a bit stringy when I removed it.