Furious Martin Gillingham, 47, posted a picture of a humorous slogan T-shirt which read: "I may seem calm and reserved, but if you mess with my kids I will break out a level of craziness that will make your nightmares seem like a happy place."<br /><br />Underneath he commented: "I think I might wear this to the next parent’s evening."<br /><br />But Mr Gillingham was amazed when two police officers knocked on his door and told him they were investigating the 'threatening' message after an anonymous tip-off.
