This might be a stupid question but I'm asking it anyway.

Has anybody had the rubber nut/bolt caps on the wiper blade arm come off?

I ask as on several occasions I have found that one or both have come off (first time round one was gone altogether, last few times either they have been just under the bonnet in the plastic vents and/or one was on top of the bonnet just at the top).

Either they are springing to life OR some fecker is messing around with my car!!

Had the rear one pulled of my dads fiesta a few yrs ago by the usual returning from the pub brigade and nothing better to do than pull everyones wipers up . Suspect you have someone playing silly buggers with you.

Then it's probably my prat of a brother being a knob then. My car has been parked up outside of our house the last 2 weeks and we live 50m of the main road down a private shared track (only our family and two owners of the fields & stables next to us come down it).

If ever you require new ones ..... https://www.fordpartsuk.com/shop/ford_focus_windscreen_wiper_arm_nut_cover_f_1324768_c_453.htm

I bought a couple a few months ago when the first time one went missing (have 1 spare). I thought it might have been somebody in town after I parked at the rear of some houses just at the back of my father's restaurant. Stupid thing is that they are £1 each but everywhere that sells them still charges £3+ postage when they would be fine by normal postage for less than £1.