Bunch of balloons halts trains.

[pre65]

Bunch of balloons on Billericay overhead wires halts trains in their tracks.

http://www.bbc.co.uk/news/uk-england-essex-43006771

[Beeyar Wunby]

NR gets very crotchety about plasticky things on the overheads.
As things go, that group of balloons is actually a very big obstruction.

UK drivers are required to call in ANYTHING that's hanging off the Overhead Line Equipment. In the past on the ECML, train movements have actually been suspended for a single supermarket plastic bag wrapped around the contact wire!

I've never been given an explanation as to why this is, but having ripped down my fair share of droppers* over the years, I know that they do detach very easily, causing the contact wire to dangle uselessly. This then tends to wrap round a train's pantograph and all the 'knitting' then gets torn down and wrapped around the roof of the train.

*(A dropper is a short vertical strap that suspends the contact wire under the catenary wire)

BW (Holder of the silver star award for pantograph mangling).

[hereward]

Those balloons look like the sort of thing they have at corporate events, they do not have the variety of colours those street vendors have. Doubt anyone will come forward to claim them though.