Janet Baraclough wrote:

Unusual to draw such a blank; but that may mean it's something that
doesn't grow in UK conditions. From what I've read, Japan's climate
combines heat with high humidity in summer and cold snowy winters, not
much like any single part of the UK. Where is Dave Poole? :-)

Not much snow in Okazaki, 1 or 2 dustings a year. Seabreezes take the
punch out of the summer humidity too. Kind of like a slightly more
temperate version of Cornwall.

You might try asking on rec.gardens, Declan; it's mostly American
gardeners there and I wonder if someone from the South-east states might
recognise it.

Thanks Janet. If nobody can identify it from the new photos just
uploaded, I'll give that a go too.

Regards Declan,
Okazaki, Japan