Bunch of jobsworths!
Could you not show them their official document that says no longer than 30cm?
You know how these things are, they are treating it all like airline security.
I actually thought in general that the volunteers, police and army were very good.
I only ran into one jobsworth today where there was a single metal barrier about a meter long which denoted the flow of pedestrian traffic when crossing over the road points when open for the road race. There was nobody crossing, yet he stopped me, and made me walk the few steps backwards around the barrier so that I was walking what is deemed the 'correct' way. It just felt ridiculous when there was nobody else walking, so it defeated the entire point of controlling foot traffic. I was laughing at how bizarre it was as I followed his request.