ID on the English infill plane...

After some googling, I think that this plane is a Henry Slater casting, being finished by a workman, circa end of 19th century.
Henry Slater made cast steel plane body for sale to other would be plane makers.
Henry and then his son Benjamin made them from 1869 to 1907. And of course they never identified (no markings nor names) these generic castings they were selling to others.
This article from Jim Hendricks shows the evolution of this form of coffin smoother. Called coffin, because the sides and/or the back are rounded. It is a very comfortable form to push while planing.

The evolution from L-R

Pic from above article

That would explain this unmarked cast body and the construction details found on this plane, more on this in a minute.

The blade could had been any from a number of makers, I don't think that Spear & Jackson made plane per se. Please correct me if I'm wrong...

The vendor identified it as a Spear & Jackson 

Rosewood infill plane

Ca 1890 Sheffield

As is, the plane has some issues, but typical of the form

The Achilles heel of this English design is the juncture of the metal sole with the wood infill. Wood and metal do not expand and contract at the same rate, after a while (a long while perhaps) the wood infill shrink and recess from the thick metal bedding sole. You cannot stop that from happening, but you can minimize it.

You can clearly see how the two wood infills 

have recessed from the metal parts

The recessed area in front does not impair its function, but it does on the rear piece acting as the frog.

The front bun, and the rear infill are now slightly recessed

 from the body due to shrinkage.

Notice also that the front bun has been made with two pieces glued up, the tell tale demarcation of wood grain is a giveaway. I guess no wood was wasted in making this plane... This point out to a craftsman made plane as opposed to a commercial maker.

Of course the frog being no longer co planar, we have some issues with the blade bedding.

See how the wood wedge cannot sit properly against the blade?

There is a noticeable gap, the thickness of the gap 

between the sole and the frog.

Two obvious solutions:
1- File back the metal part until it lays flat with the wood again. Not recommended, or
2- Shim the wood bed part until coplanar. What I will do.

Why not just file it? It would open the mouth and erase a design flaw... temporarily, wood always move. Although that piece of infill is probably pretty dry by now...
Still as much as I intend to put this plane back to work, I do not want to erase its quirks, for historical purpose... I am but the current caretaker of this artifact.

The wedge shows some strange grain directions, then on closer inspection, I realized that the wedge is made up of two parts glued together.

See the glue line on the side of the wedge?

I was wondering about the strange grain directions 

in the back of the wedge... 

See what I meant by not wasting any wood :-)

The blade has plenty of life left, 

unless I grind it on a grinder each time :-)

Note the old style blade, the bottom cut out is nearly square 

to accommodate the solid square nut.

The nut is captive on the cap iron

S&J called it Solid nut

The blade and cap iron have been fettled somewhat.

Cap iron fits pretty tight on the blade, should not required much work to make perfect... Famous last words...

The tapered blade is nearly 1/8 thick at the edge (5/32) and tapered to 1/16 at the heel. A hefty solid blade.

As expected, this plane pack quite a weight for its compact size.

3.054 Pounds

But perhaps surprising was the comparable weight of a similar sized Record No 4 SS...

Which in fact is slightly heavier...

3.149 Pounds

Seen side by side for comparison

Cast Infill is 7-1/2in long X 2-5/16 wide

Blade is 1-15/16 in wide

Record is 9-1/4 long X 2-7/16 wide

Blade is 2 in wide

But what about a similar sized wooden coffin smoother?
Glad you asked :-), here are the comparisons

Typical British Wooden coffin smoother of the same era,

Nurse & Co, Invicta

2.026 pounds.

No surprise there, it is lighter, by a good pound.

This woody is 9 in long X 2-3/4 at the widest, down to 1-3/4 at each ends.
The blade is 2 in wide. These are comparable sized smoother, which were all available at the same time (Bailey Stanley smoother was pat in 1867)

Their various height and weight, and the location of our hands on them make them all behave sensibly different in action. It was and is still, a matter of preference.

Back to our infill...
The sole is in good shape and the mouth area is still crisp.

The only apology to it, is a small chunk missing from the rear infill on the top, but it does not impaired or make it feel uncomfortable to use. I will then probably leave it as is. That area is so worn out smooth  around it, it must have happened a long time ago... Guessing it was from using a metal hammer to adjust the blade.

All in all, it has all the DNA to become a good smoother plane, can't wait to road test it... but, unfortunately, I must make some headway with my new stashes of tools accumulating everywhere...

Somewhere under there, there is a bench, I swear :-)

Both pics are from my man cave were every flat surfaces

  has becomes a magnet for tools

But this is suppose to be vacation time, so it will be slow progress :-)

Bob, who need to kick in his inner OCD :-)