With regards to the TPD I still feel that the most important parts of the legislation are
Regulation 36
(2) Nicotine-containing liquid which is presented for retail sale must be in—
(a) a dedicated refill container in a volume not exceeding 10 millilitres; or
(b) a disposable electronic cigarette, a single use cartridge, or a tank, in a volume not
exceeding 2 millilitres.
(3) The capacity of the tank of a refillable electronic cigarette must not exceed 2 millilitres.
Part (2) above is fairly easy to digest and interpret - If it's got liquid in, when presented for sale, then it's 10ml for a bottle of juice and 2ml for a tank. IMPORTANT - Part (2) only applies if the bottle, or tank, has e-liquid in!
Part (3) is not so straightforward to interpret, BUT SHOULD BE when taken at face value without the restrictions of worry gutting and mithering! Part (3) CLEARLY states that the tank capacity of a "Refillable Electronic Cigarette" must not exceed 2ml (whether it's sold with juice in or not) . No problem understanding or interpreting that.
BUT - A tank on it's own, with no liquid in it, no battery, no electronics and no means of operating as an electronic cigarette, is NOT AN ELECTRONIC CIGARETTE.
Take the TPD at face value and implement what it defines, and NOT what you think it defines will be, in my opinion a very wise move.
ps Regulation 36 Part 10 (b) which clearly states that the juice bottles (refill containers) operate by means of a docking system which only releases refill liquids into the tank of an electronic cigarette when the electronic cigarette and refill container are connected will, for the mitherers, prove to be a huge headache and mind fuck
Shhh!