As I mentioned in a previous post

1) I have acquired an old rusty plane. It is 14" long and has No5 in relief
just ahead of the front handle and no other markings. The handles are wood
and the sole plate is ridged. Any ideas on age, quality etc.? Is it worth
sharpening as a beginner project?

Based on all of your valuable feedback I figured it must be a Stanley No. 5
plane from the 1930's.

As I cleaned it up I noticed that there is in fact an additional marking.
The blade has 'Siegley' with 'S s S' beneath on the end. So:
Is it a Siegley plane or a Stanley plane with a replacement blade made by
Siegley?
Does this change the dating estimate?
Are Siegley blades higher or lower quality than Stanley blades?

Any help greatly appreciated.
Jack Fearnley