Beg to differ Reg...
"especially sites that don't run ads, may come to different conclusions"
Whether you choose to carry ads or not, using SSL in the UK is (sadly) essential if you depend upon the web.
Unlawful use of DPI by UK ISPs can be used to strip your customers/visitors/readers from your site (by competitive intelligence gathering), rewrite your ads to steal affiliate income, or even overwrite your content/ads with 'fewer, more relevant' ads from shady Russian/Chinese/Turkish spyware developers (ahem).
And - without SSL - you have no protection. Because the UK Police, regulators, and Government don't care...