SoCal, what ILOC meant, and I think he's right in this case, is that any ICAO PPL is *automatically and implicitly* validated under the ANO (with the exceptions and limitations noted). So you do NOT have to make an appointment with an FSDO for a short visit, nor do a BFR, nor get an additional bit of plastic or register your details with the UK CAA. Your original (valid and current) FAA PPL bit of plastic is all that you need to fly a G-reg, worldwide.
With the FAA, the validation process is a process requiring several steps. Easy, quick and cheap steps, I'll grant you that, but you still have to go through them.