Trough holders

[brentfordfan]

I want to buy some metal holders that will hook over a balcony or fence and hold a trough.

My guess is they would be the same kind of ironwork that is used for mangers that screw to the wall and have a liner in them but these would be rectanguler and trough shaped and have curved hooks for hanging them over something rather than straight fittings for screwing them to a wall.

I have asked everywhere about these but cannot find them in Wickens, B&Q or Homebase and have drawn a blank on the internet. I've seen them a lot in Paris where people can buy trough shaped ones or single ones for pots.

Can anyone help?