In the UK, it is always very easy to find individuals who jump on the smallest opportunity to make a job out of something totally worthless and pointless.
A lot of stupid and ultimately meaningless "standards" originate elsewhere in Europe
ISO9000
CE
RoHS
but the UK is fairly unique in that it has an apparently unlimited number of people who see even the most generally pointless or even damaging measure as a job/business/consultancy opportunity.
I suspect this is not an insurance requirement as such. It is probably some useless little man walking around with a writing pad, who had landed the wonderful job to oversee their health & safety policy and make recommendations, so they can show due diligence if something cropped up.
Imagine the stupid scene where a family of four turns up. They will have had to go to some pilot shop and purchase 2-3 different sizes of these stupid yellow jackets.