Ian, as you can see I modified your above post to put the first two images in line.
The first was done by adding
attachthumb=1 (put this in square brackets) ***
where I wanted the first image to go
The next was done by adding
attach=2 (put this in square brackets) ***
this put the full size image in this place.
You just keep adding 3,4,5 etc and attach the images in the same way as before
*** That is [xxxxx] - can't enclose the commands in this example because it starts looking for images that are not there!
You won't find this in the help as it is a non-standard addition.