For what it's worth, the two pianos described by John Rutoskey in
MMD 181213 (a purported Mason & Hamlin upright and a Windsor upright)
are not quite identical, at least as far as he player action goes.
From the photo of the "Mason" spool box, it appears to have tracking
"paddles" above the tracker bar, while the Windsor has a transposing
tracker bar with fixed tracking ports that "slide" in horizontal slots.

This is not to say that Windsor did not switch player action suppliers
at some point, which is certainly possible.  There is, however, no
denying the similarity of architecture of the two cases, which is likely
definitive for Windsor, so I would concur with John's conclusion.

Whether the player action is Pratt-Read or some other, the basic
instrument is highly unlikely to be a Mason & Hamlin.  A serial number
would be helpful.  Again, for what it's worth, the only upright Mason &
Hamlin I have seen was a Welte, although I don't recall what version.

John Grant