Those servo screws seem to be Pozidrive which is nowadays much more common than Philips in Britain. A number 0 (zero ) Pozidrive screwdriver fits well.
However to initially start these small screws in a servo etc nothing beats a ' pearlcatcher ' or ' pick up tool ' a tiny gadget with three wire claws which will hold any small object and grips firmly enough to start the screw.
An essential gadget for the modeller!

Whats wrong with Whitworth? Do not forget that Mr Whitworth pioneered standardised threads---before him every machine had its own threads and was non interchangeable. Every camera from Victorian times to the Leica and to the latest digital model seems to have Whitworth threads on it - the tripod bush is 1/4 or 3/8 whit, usually 1/4. For the record if you ever need a Whitworth tap or die they are easily obtained from British model engineering suppliers, but of course Metric threads are now the standard worldwide.