Thank you both for the feedback ... This is only the second attempt I've had at a proper shoot and I'm still on the steep end of the learning curve!
I was struggling with balancing my flash lights against each other and against the natural light. Part of the issue is that my flashes are OLD ones (reaaaaaaally old) that have no kind of power adjustment; it's all or nothing. (The three have listed GN's of 28m, 29m and 17m).
On #1 and #5 I did want to use my softboxes but the wind was very strong and it seemed I couldn't weigh down my light stands sufficiently for them to stay standing, so I ended up with just a bare flash. Unfortunately that meant I could have only balanced the flash properly with the natural light if I'd had a stupidly long shutter speed that was going to cause motion blur.
On #1 I like the way the flash accentuates the pattern of the background with shadows, but would like to have eliminated the brighter area top-left ... I'm actually not totally sure how I'd do that though.
On #2 I didn't even try it with the softboxes but should have done - I was just being lazy.

Next time ...
I also needed to get more light onto his legs; I'm not happy with how much darker they are than his top half.
I had a few attempts at the running shots and didn't quite get exactly what I wanted on any of them.
On #3 the lighting was deliberately harsh and overall I'm pleased with the result; I'd have liked to have kept more detail in the bright areas of his shirt though.
I don't think the lighting's harsh on #4 ... I had two softboxes quite close to him (there was a bare flash pointed at the background too) ... I did notice that the suit was not very well fitting but everyone else seemed keen on getting some suited shots so I gave it a go. The spillback of light from the wall is a little extreme on his edges at the viewer's right though. I guess the easiest way to cut that down would be a greater distance between subject and background, but that wasn't an option in the space I had to work.
I actually really like the look of #5 with the bare flash; not to say it couldn't be improved on but I'm pleased with how it came out.