So I spent some time on t’internet and information was gathered and  though sparse due to the age, I’m now a ’38 a MOPAR expert!
No not really but there is quit a bit of conflicting or duplicated info on the model range , particularly where the years ended and new ones started.
In brief: In the late 30’s the USA Plymouth brand was sold in the UK under the Chrysler badge.
At this time there was still a UK demand for premium cars that outstripped UK supply and to circumvent import duty these cars were imported in “kit” form.
Depending on the model and where they were built was part of the naming convention. Chrysler UK had a factory in Kew Gardens, London.
So, keeping it relevant to this car, the Plymouth P6 was sold in the UK badged as as the Chrysler Kew.