Changing drive belt on mountfield / stiga / castle garden lawn tractor 1430/1436/1530

No videos on here on how to do this job, just the odd one about adjusting / reseating the belt. So I thought it might be useful for someone else to see how I do this job. This works for the models listed, no doubt it will be similar for many other models.
Small correction at 40 seconds I refer to taking the drive belt off first, of course, I mean the cutting belt, not the drive belt.