Actually the caa ban all christmas crackers on any flight due to the stick inside them could spark causing a fire but this abstract is from a caa document on the matter
1.3 Christmas Crackers and Party Poppers
1.3.1 At this time of year the Authority is often asked about whether Christmas crackers can be carried by
passengers and whether operators can provide them to passengers with their meals at Christmas time.
Christmas crackers when complete and in their retail packaging (ie: in a box of Christmas crackers) do
not have sufficient grains of explosive in the "snap" to be regarded as dangerous goods and they can be
carried without restriction. However, the snaps when shipped on their own are regarded as having an
explosive potential because of the number likely to be contained in a single package and they need to
be consigned as dangerous goods under the classification assigned to them by the relevant competent
authority and in accordance with the requirements of the Technical Instructions.
1.3.2 The Authority is also asked about party poppers; even though they may appear to also contain a
minimal quantity of explosive, tests have shown there is sufficient to give rise to a hazard similar to that
posed by toy gun caps. Therefore, they are not considered to be suitable for carriage by passengers in
their baggage and, even in their retail packaging, need to be consigned as cargo in accordance with the
requirements for dangerous goods.