I was given one a while back it said on the label spreads slowly. So I put it in a border. The damned thing spread over 5' in all directions over the winter and started appearing in amongst a clump of alstromeria and another clump of delphs the other way, and on the lawn either side of the border. So it was dug up and put in the OM's wood where it can spread to it's heart content. So my suggestion would be to keep it away from your border.

Very valued advice - thank you very much. I had a horrible suspicion that it might be like that. I was considering a place to itself in the lawn, but maybe even that isn't such a good idea? I guess you could mow the suckers off as you do with the stags horn sumach?

well I haven't any in the lawns since I been mowing it and also since I moved Mum. So Yes that would be fine.
But bear in mind it spread a good 5' either way over the last winter. How far would it have gone if we'd have had a mild winter. Lock your back door it could be coming in, in a few years :-)

I will put it at the bottom of the lawn then, well away from the house. The utility room would be its first point of entry and it is far too small for anything else at all to go in there! Five feet each way in winter is amazing.