But I can't download it.
I have just uninstalled Filezilla and tried to re-install it with a view to seeing whether by doing that it would bring me up the software download option, but McAfee is blocking it now and telling me it contains harmful files - which didn't happen the first time I downloaded Filezilla. It did give me the option to continue anyway, but if you pay for virus protection there seems little point in overriding it when it tells you all is not well.
I have decided to cut my losses, admit defeat, and see about purchasing the DVD instead (which means it isn't, strictly speaking, free any more, but 20 Euros really is a small price to pay for such a fabulous program).
I just hope that when I receive it I won't get the same brick wall from Windows when trying to install from the DVD.
Thanks to all who have tried to help - sorry that on this occasion it hasn't worked out.