Simon - that is one way (open review post). Quicker way is:
1) right mouse click on pic in "attached thumbnails"
2) Note 2 things:
-- Copy Image Location: This is your thumb https://forums.clubtread.com/attachme...1&d=1418618769
-- Copy Link Location. This is your full blown pic https://forums.clubtread.com/attachme...6&d=1418618769
These 2 properties are actually the same, except for additional thumb=1
So if you want to show thumb, put "Image Location" inside "img" tag. I.e
If you want to show full pic, put "Link Location" inside "img" tag. I.e