Britannia D900LMP Oven Lower Heating Element replacement

My oven was struggling to get above 150C and I determined that the lower element was not working. Britannia offer a replacement element for £130 but, given the age of the oven, I opted for a (new) generic element for £35. I had not intended to make a video but my family was intrigued to see how I got on with the replacement and I thought it might be useful to others looking to undertake the same task - so here it is ....