Thanks Gonzo! I've already sent it in... I've put the last 5 years - these are the 3 jobs that have led me to be in the position I'm in and certainly the most relevant(ish). Wish I'd read your reply first but too late now.
I guess a concern was that in my current industry (financial services), it's normal for good people to change company every year or two. In fact you wouldn't want someone who was so rubbish that they weren't poached at least every few years! This (NATS) is quite different for me and I hope I get the chance to explain that to an interviewer.