I used a heavy duty wire brush on drill of some Victorian cast iron gate posts - worked a dream. Down to shiny metal in no time. The
Halfords items linked upthread are a bit whimpy - ok for fine detailing but not heavy lifting,
The kling strip linked upthread gets good comments:
I ordered Kling Strip feeling a bit dubious that it would remove all the paint from an iron fire place based on my experience using a Nitromors type product. I was delighted at the result though! Kling Strip removed a number of layers of paint, including what we guessed was lead based paint. The majority of the product brought off the paint in one gelatinous length. It was a little messy to remove the remaining product, and you will need to use a nail brush or something less abrasive to get all the product off. However, if you are looking for something to remove all traces of paint, this product will do the trick. NB Protect walls and floor coverings around the area to be stripped.