Smee, if it’s causing an obstruction, it’s most probably going to be down to the police to sort it, if you can get them to respond to it.
PDF, technically yes, TMA 2004, however, local authorities might not yet have adopted the powers, I know mine are stillin the process.
TT, I find it near impossible to find two coppers who agree on what the details of obstruction are. Most don’t even know it’s their responsibility and pass you onto the local authority, especially if they cover parking issues.
Fagus, not strictly try as what they’ve done is obstruct the highway. I think this one is RTA 1984. The local authority has the power to remove it, especially if it’s chained to their lamp column.