I suspect they are referring to the “Boat Safety Scheme” which is run by Canal & River Trust and Environment Agency, which can be found at www.boatsafetyscheme.org
The scheme at the moment only applies to boats using inland waterways, however you can apply for an exemption certificate if your boat fits certain criteria. See www.canalrivertrust.org.uk/media/library/733.pdf
Whilst most boat owners on here are knowable about boat safety and maintain their boats to a high standard, but I have seen boats bought by newbie’s to boating that certainly aren’t safe and are not fit to be used on any waters, further more nor are they aware until it's pointed out to them or the inevitable happens.
Whilst this country is a rapidly changing place, I doubt it will be long before insurance company start insisting on insured boats having some sort of safety certificate or survey be it for Canal, river or Sea use which I suppose is not a bad thing.
May be this is the start of something new?