Thanks for posting this. I was unaware of the existence of the Gosford Park fansite.
I had thought Lady Trentham was referring to the silent 1926 The Lodger, which I've seen on youtube, when she was actually speaking about the talkie remake, The Phantom Fiend. They call it The Lodger in GP, probably because the general public would not recognize the latter title. Now that I have this correct information, I have found it on youtube and will watch it.