I attacked them today, and got them all off, plugs changed, new coils fitted, all working well. Cyl 3 was the easiest for access, so attacked first. Rubber boot was stuck tight, and just stretched. Tried compressed air, no joy. So just severed the boot with a sharp knife. That left me with about a centimetre of boot above the plug top. Filled the centre with WD40, then slid a pick down between the boot and plug, working my way around. Still stuck. Got the fatter, long pick, and pushed that down, all around. Suddenly it let go, and the remaining boot could be twisted and lifted. Absolutely no trace of silicone grease on boot or plug. As these were the original coils, and the plugs have been changed just once before, it appears that they were not just fitted without grease, but probably wiped clean. This being a Skoda specialist, that used to be a dealer. No point shaming them, owners retired, garage shut. Having got the first one out, it was apparent that the coil can be separated from the boot. For the rest, I gently levered the boot off the coil, leaving just the boots in the head. That gave a larger reservoir for WD40, which may have helped, or just made more mess. Long-nosed pliers pulled the springs gently out. Then large pick pushed gently in, all around to separate boot from plugs. Took a lot of time, but at last all four removed. All clean of grease as the first one. All boots damaged by the pick, as there is little control over it, so scrap anyway. They show a VW part number, I'll research tomorrow to see if new boots are available without coils. Plugs came out ok, a bit tight, but the new ones went in fine, so no thread damage to head. New coils, properly greased, all back together and running well. Took about 3 hours, for what should have been 30 minutes. This is a job for taller mechanics. Knees pressed against the bumper, leaning over and stretching a little, is not comfortable. I now ache across the shoulders, my neck, and the backs of my knees. Happy days.