Thanks for the info, but it turns out it was not a takedown as such.

There was no lever near the trigger guard. The wedge was the type with the spring. But the rear action screw went all the way through and into the bottom of the action.

The tang did hook under a secured section screwed to the stop.

Doesn't matter any more now. What I though would eventually happen did happen , but a lot sooner then I had hoped. I needed the money and sold it.

Pity, nice old thing.