That's something I don't mind - I've said so before and I still think so. My concept of it's operation is that a rating is self-assessed and added to metadata of each protocol, except e-mail and instant messaging or similar "person-to-person" protocols. Some will criticise self-assessment, and, yeah, it's not perfect, but spot checks run by Ofcom (in the UK) or ACMA (in Australia), and whatever other agencies do those jobs elsewhere, can help "keep the system honest". Of course, the most important thing to make ratings work is to provide clear guidance on how to rate material. As to subordinate pages or frames, they can all have a rating in the metadata - I expect the default setting would be to inherit the parent rating. Therefore, bookmarks would be "rated" no matter where they pointed.
If we keep in mind that, although there are lunatics and criminals out there, the vast majority of internet page authors are reasonable people who, with a bit of convincing, could adopt a ratings system for content that they author - providing the standards and tools support making their adoption easy.
Ratings (again, although not perfect) would allow fast filtering of a great deal of content which makes other filtering less resource-intensive.
Yes, it is an imposition, but ratings do not of themselves limit free speech .... PROVIDED THAT NO SERVICE PROVIDER CAN BLOCK MATERIAL OUTRIGHT WITHOUT THE SUBSCRIBER'S CONSENT. I see a ratings-based filter in its simplest form being a password-protected browser setting , or a filter in a proxy/in-line filter device or an ISP filter (if opted for by the subscriber).
I MUST STRESS THAT ANY FILTERING MECHANISM SHOULD BE "OPT-IN" AND MUST BE ABLE TO BE COMPLETELY TURNED OFF BY THE SUBSCRIBER IF DESIRED.
On the other hand, if online material is rated, then so should be books, all magazines (not just ones with nudity) and newspapers. Consistancy would be appreciated.
Note, though, that IMHO, the whole filtering argument is not about "protecting children" - it's about CONTROL. Politicians see something and just can't help themselves - they have to control it - therefore they have to pander to lobby groups or other vested interests in the process.
As to the rest of Burnham's comments - yes, he does seem to be quite a twat.