Ford Focus Mk2: How to replace the thermostat | 1.6 petrol

Since getting this Mark 2 Ford Focus 1.6 petrol, I've noticed that the engine takes a very long time to warm up, particularly in cold weather, and also fluctuates a lot while driving. I suspect that the thermostat is stuck open, meaning that coolant is always flowing through the radiator and causing the car to take longer to get to temperature.

In this video I set out to change the thermostat out for a new replacement.

00:00 - Symptoms
00:49 - Plan of work
01:35 - Remove power steering fluid reservoir
02:06 - Disconnect battery
02:18 - Slacken off alternator bottom bolt
03:21 - Remove alternator top bolt & nut
03:32 - Remove alternator securing stud
04:10 - Remove terminals from alternator
04:34 - Remove alternator
04:59 - Drain coolant
06:12 - Remove coolant pipes
06:22 - Remove thermostat housing bolts
07:07 - Remove thermostat
07:46 - Install new thermostat
08:00 - Refit thermostat housing
08:09 - Refit coolant pipes
08:37 - Refit alternator
09:07 - Refit coolant drain plug
09:15 - Refill coolant
10:14 - Results