@Kat, cutting them isn't the problem as I'm entirely comfortable with doing that (I buy whole chickens and joint them rather than paying over the odds for individual bits!), it's getting them to a sensible size that I need quantifying. I've since asking opted for around 4cm but I'm now waiting for some half-way decent weather so I can cook one of them and see how it goes before accepting an answer =)

Thanks for taking time to answer, but.... "try it yourself and tell us what the result is" doesn't exactly answer my question; particularly as I'm at pains to point out in the question that this is because I'm low on plain flour and have plenty of self-raising. For info; I haven't seen plain flour in my local supermarket(s) for the best part of two weeks (hurrah for people panic buying!) and I'm loathe to buy what others may need when I may have alternate options. Now is not the time for me to waste by trying =)

@bob1 I was reluctant to be any more specific (Weber gas BBQ, medium heat, so happy to add more detail!) as I'd then potentially start getting into the realms of adding how long the steak is at room temperature first, how long the BBQ is generally pre-heated for, etc, and if the question is answerable without said specifics, or they become part of the answer, then that makes them moot or unhelpful in the question =)

@GgD, I don't mean to be rude, but perhaps you should re-read my question. I'm not asking "how thick do I like my steak" at all. The fact that my question is seeking clarity on the thickness of the steak in order to meet other criteria should make it abundantly clear to you that I don't care how thick the steak is. As for completely opinion based, given enough steak and time, this question could be answered experimentally (as noted in the final para), so again, no.