I am not aware of any distinction in the legislation between session cookies and persistent cookies. The key attribute is rather the purpose to which the cookie is put.

If session and persistent cookies are regarded differently, it would be useful to know about it. My reading of section 6 of the PECL suggests otherwise though.

My reading of that section (specifically s6(4) which has the exemptions) is that because persistence or otherwise is not mentioned, it's not relevant.

The only slightly obscure thing is it refers to "provision of an information society service". That appears, from the full text of the directive, to be a vague thing semantically equivalent to "an information service". Therefore, anything "strictly necessary for the provision" of one of those is exempted from the explicit consent bit.

I am not aware of any distinction in the legislation between session cookies and persistent cookies

My knowledge of the legislation is only partial. It is our intention to comply with it, but more important to us are the Google data layer requirements as we rely on remarketing code. Google seem to require a popup distinct from a banner and don't seem to like persistent cookies. We did some tests a while back but they perhaps weren't totally thorough as we made some assumptions.

The way we implement cookies is to present a small popup right at the bottom of the screen if the user doesn't have our cookieConsent cookie set. If they click no, we set that cookie to false or if they click yes, we set it to true and make it persistent for one year. From this we determine how we set other cookies - mostly to either make them persistent or not. Not that we use a lot of cookies - one for a banner popup and two for login purposes.