Here are some side by side pictures, and I'll also talk about the fit of each shoe on my right foot (wider of the two, D and a half width, borderline E). I'm a 9.5UK Rain and 9.5UK everything JFP, F width in GG.
Before my pictures and comments, I'll copy what Justin says about sizing on his website (http://www.jfitzpatrickfootwear.com/pages/size-guide
J.FitzPatrick shoes have a very standard fit. Our sizes are based on the UK standard where ‘E’ is the “medium” width being equivalent to a US ‘D’ width. If you have always been size 10, then this is what you should expect to be in our footwear as well.
All five of our lasts were created on the same body, only changing the shape of the toe, thus ensuring a standard fit from heel to ball of foot, across all models. However, one must take into account that loafers will fit differently to oxfords and oxfords will fit differently to derbys, so while you may feel good in the fit of an oxford, the same size in a derby might feel loose due to the extra room in the instep created from the open lacing.This has nothing to do with size however, but more so the nature of the different models in footwear. Understanding this will help you choose your size more accurately.
The TMG last is the most classic fitting last fitting very standard. The LPB and MGF due to having to elongate the toe box to create them will be the most generous in the vamp/toe region. The JKF will be the tightest across the toe region. All shoes with 6 eyelets will be more generous in the instep. Any model in full suede will feel more generous to its leather counterpart. The boots have a forgiving instep in order for you to get into them easily. The monkstraps as a model and because they are usually one the LPB last will be the most generous fitting models.
For my part, left to right: Wedgwood (TMG), Carmina 922 (Rain), Wallingford (JKF), Rainier (LPB)
Between Carmina's Rain and Justin's last, the biggest difference to me is a higher instep and narrower heel.Carmina 922 (Rain)
-Normal fit, widest part of foot (ball) is at widest part of shoe
-Heel wider than I'd like, had a lot of heel slip breaking the shoes in
-Laces don't close all the way due to my slightly higher than average instep.
-I have about 1/2inch from big toe to end of shoe and the taper of shoe where the bottom of the "U" shape of the wing is is where my second to last toe isWedgwood (TMG)
-Very close to Rain in terms of width across forefoot and overall length
-Slightly narrower through the arch/midfoot so the shoe hugs my foot better, since it's narrower from the midfoot back, is has a subsequently narrower heel than RainRainier (LPB)
-Narrowest, most elongated JFP last IMO
-Fit is same as TMG except toe is narrower, if you need the full room of Rain I'd not go with LPB
-More length in the toe than TMG/Rain but with the taper starting earlier/being more extreme, you get less width across the toe box.
-Instep height is equal to TMG and Rain (laces have a gap of less than a centimeter at the top, but do not close all the way)Wallingford (JKF)
-Symmetrical taper gives a hair more width in forefoot than LPB, but still more tapered than TMG
-Keeps width longer from the ball back to the heel than my other JFP shoes, not as snug under the arch. But this could be due to the suede in the shoe having more give than leather.
-Highest instep of my JFP shoes (agrees with Justin's description above - 6 eyelets), no lace gap at all. Any higher and I'd want an insole so they wouldn't be too loose.
Hope this is of use. If anything I said doesn't jibe with Justin's sizing info I'm sure he'll jump in to clarify.Edited by Shawl Lapel - 3/21/17 at 4:07am