Many thanks for the votes and comments on yesterday's Silver Spotted Skipper and especially to Ade for the UA, all are most appreciated.
This colourful critter was crossing the mountain road in front of me in Miraflores last month. It's the caterpiller of a large (mostly white) moth known as Cerura iberica. One of it's defence mechanisms is to spit formic acid at an attacker if provoked, something that i experienced as i placed him on the branch.
Off to Spain first thing tomorrow morning, hopefully to find some new butterfly species.