It is certainly worth a try Robert. I am doing the same with a few of mine.
A couple of years ago I let a Grosse Lisse go through winter in my unheated greenhouse then at the end of winter cut it off about a foot above the ground, it shot again and produced all the next season.

Mantis

You've got nothing to lose, Robert. I have an Anna Russian plant - planted out back in September - that had been nearly totally destroyed by Early Blight. It was 99.9% brown and withered. I was about to yank it when I saw some fresh, green growth down the bottom. I cut it back to the fresh growth and now it's 4' tall, green and healthy, with flowers starting to appear.

Mantis - did you get any fruit on the Grosse Lisse through the winter or just when it warmed up again?

Amanda, I got fruit well into winter but they slowed rapidly with the cold weather. They grew ok, but I had to bring them inside and put them with some apples or bananas to get them to ripen. Slow and painfull stuff. I am going to try it with a Brandywine suddeth growing in the corner of the GH, hopefully to beat, oh ,um thats right, Finbar wont be here next season.

And I'll be getting there too late for a crop this northern summer! *spewing*

Couldn't you smuggle a few early type seeds in the socks or something?

finbar, that really depends on when you are going there. Things don't start until April/May or so. Depending on the exact location, of course.

No need for smuggling. You can bring in seeds without a problem.

I find it extremely hard to feel sorry for finbar, regardless of whether he can grow tommies, he'll be living in Italy!
I'm very much hoping that my grandmother will require my assistance to emigrate to NZ so I can travel back to Europe & pay finbar & Robyn a visit :-)
(especially as my Mum thinks she'll be travelling business class!)

No, taking seeds in isn't a problem. But, after lots of changes of mind, we're probably going to take a place for a couple of months to use as a base to find somewhere longer term. By the time we're settled wherever we finish up, it will be too late to plant anything other than earlies. By which I mean, we're not going to be any further south than Umbria.

Robert, just wondered what you decided to do? Rip 'em out or prune 'em back? I've a couple of dwarf types setting new growth. I thought they were determinates so I wouldn't be likely to get another round of fruit set. But perhaps they're dwarf indterminates - is there such a thing? Anyway, I'll let them go and see what happens.

How big are they, Ray? There are compact indeterminates. Stupice is one. Where was your fruit setting on the ones in question?

Raymondo, I am pretty sure they are indeterminate, which leads me to believe that the odds are, I will get more fruit if they come away with any vigour. I am also going to wack them with some manure as well.

Robert, definitely yes for indeterminates. You should get more fruit set.

Finbar, I've just looked them up and they're listed as determinates so I don't think I'll bother. I still have one of Richrd's Polish plants on the deck. I'll give that a prune and a good feed and see xhat happens.

Are Grosse Lisse a heirloom variety?

Yes, they're usually open pollinated, although I gather there are hybrid versions for sale in nurseries, producing smaller fruit than the OP version.