Hi Chris, good to know.
For the vehicles you are looking out for, you need the more specialist outlets such as Ken Jenkins, trading as UK Jag. Ken has a steady supply of these type of machines and is currently advertising a 1959 XK 150S, 3.8 Roadster (not a DHC). He is advertising a 1954 XK120 DHC 3.4. the website is www.ukjag.co.uk
There is an XK150 DHC SE 1959 advertised in the JE magazine - in the Norfolk area.
N6 JMX