One school of thought is just keep quite and take your chances.
Personally i would call ahead. A lot of people disagree with me but at the end of the day I don't want to get in **** for trying to take something on to a plane that could be misunderstood. People have had to pay money in the past because of this, admittedly it could have been avoided if no one had enquired, but you can't control that so you are taking a risk.
Heston called up easy jet and had no problem, they contacted the checkin desk and advised them to let him through.
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I would rather be told that the airline won't let me fly with my marker before i have bought my tickets so that I can try a different airline. Speak to easy jet, mention that you have been told they are happy for people to bring disasembled markers, and ask them to make sure the checkin desk are aware of this policy, even get an eamil or letter off them that you could show the check in desk.
You could also try calling the UKPSF, they might be able to give you some more advice.