Unusual Insurance requests

[Gog]

Bit of an odd one this. A friend has a large stone planter that they want to put outside their house (on a pavement). She has asked the Council if they can do it, and they replied that it would be OK as long as it was insured for claims etc. She has asked loads of companies but nobody really seems to do such things. Any body got any suggestions of a company to ask for a quote?