I think the biggest thing that says not a bomb was that he asked permission _before_ bringing it in[1].
[1]https://twitter.com/AnneClaireCNN/status/644158607035133952
[1]https://twitter.com/AnneClaireCNN/status/644158607035133952
http://news.bbc.co.uk/1/hi/uk/7030096.stm
http://www.bbc.co.uk/news/uk-england-manchester-33705944
(The explorer Sir Ranulph Twisleton-Wykeham-Fiennes while on service with the SAS used to work out how to efficiently use explosive, allowing him to keep small amounts after training exercises. He accumulated a small stock of explosive which he used to demolish an ugly damn.
https://en.wikipedia.org/wiki/Ranulph_Fiennes
)
Anyone have a guess what that thing actually is?