Thanks Randy, i've imported a few cars from the UK before, so thats not a problem.
Eric, you may need to excercise some caution here. I suspect your previous imports from UK were cars that had been registered in UK prior to them leaving the country. And transfers between EU were tax free so no import taxes on your side.
In the case of a car that has just been freshly shipped in from Japan one needs to get a valid MOT before you can apply for UK registration documents. And if the car requires a lot of work, then getting the car to a MOT fit state could take months if not years!
I believe that such an import could leave UK still unregistered and with Japanese registration documents. I would expect in such a case Dutch authorities would ignore the UK transit and treat it no different to a direct import from Japan and levy appropriate taxes thereby effectively putting you back to square one.