I agree with Mike that the 1857PT referenced as “much smaller figures” by Spinks in 1895 must be the same as the one shown below, known as Gouby Date Style E, with the tall slim 7. This can be compared to the picture directly underneath, an example of a larger numeral type for this year. Each has been shot at the exact same 60x magnification, with same 1280 image widths, so that a true comparison of the dates can be made. I have tried to centre each coin so that the larger border tooth is 4 teeth from the right hand side of the images.
I have spent my spare time over the past couple of days carefully going through my images of all 1857 penny ebay sales over my 5 year study period. Nothing from this sample of 621 coins appears to have smaller numerals than seen on Gouby Style E.
In this sample there were 66 Gouby Style E pieces, around 10% of the entire 1857 population.
In my 5 year study period this 1857 Gouby Style E sub-variety actually appeared less often than say an 1846, 1845 or even an 1843. The numbers are more on a par with an 1849, or 1853 Plain Trident. This may surprise, but perhaps partly explain the 1895 Spinks wording.
One other thing that I noted was that Plain Trident 1857’s represent 68% of the population, slightly at variance with Bramah’s observations where he states on his Page 109:-
“for 1857 the P.T. are commoner than the O.T. as about 3 to 1, and the latter may be regarded as scarce”.