Carrying fake guns in public (presumably bb or paint)?

I have a neighbour who lives alone and drives trucks. He also like to dress up like a soldier and carry riffles and hand guns around our estate though he is not in the TA or the military, just a local fake gun club like paintball. It is a little scary as we live next to Hungerford (hungerford macre) to see this slightly odd chap dressed up with fake guns (though they shoot ballbearings). Should I call the Police? Or is it perfectly legal to carry fake guns in military like clothing outside of a club...please advise