I've always found popping the uni in a large dustbin liner sufficiently
disguises it to allow it on almost all public transport. I used to do
this a lot on the tube; it's amazing how many ticket inspectors count the
thing as a bike if they can see a wheel; cover up the wheel and you're
away! Even for a giraffe this is sufficient disguise (but remember you
can't take items larger than 6' on the tube without prior arrangement).
pab.