Thread by @vivamjm

@PatrickBaines4 Here is that Spitfire List

Mk1 (Battle of Britain) Merlin engine 3 blade prop

Mk 5 (first with clipped wings version) Merlin 45
Mk 9 (4 blade propellor) Merlin 61?
meant to be interim model using the Mk 8 engine in Mk 5 airframe quickly thrown together to combat the F190A that outclassed the Mk 5. It went on to become the version built in greatest numbers

Mk 7 High altitude version (like Mk 6) with extended wingtips. 4 blade prop

Mk 8
Pinnacle of Merlin engined versions. 4 blade prop and first with retractable tailwheel. Used in Far East Theatre and by RAAF (and by USAAF in N. Africa/Sicily) while Mk 9 used in European Theatre

Mk PR 11
Photo Recce version used by USAAF in Europe
Merlin 4 blade prop. Deeper oil cooler to chin

Mk 14
First major production version with Griffon engine. First with 5 blade prop. Longer nose for new engine and wider stabiliser tail. Full & clipped wing version. a FR version. First with bubble canopy

Mk 16
Mk 9 built with American Packard version of Merlin

Clipped wings, bubble canopy, pointy tail

PR19

Recce version with Griffon . 5 blade prop

Mk 21

First with the brand new wing. Much bigger tail
Too late for WW2

(Mk 24 bubble canopy version here)

and naval versions
Seafire Mk 3 (Spit Mk 5) first with folding wings
Seafire Mk 15 (Spit Mk 14)

and here Seafire 47 (Spit Mk24)
**Contra rotating props**

I could have done more and given more detail but way past my bedtime now...
Other even more nerdy Spit nuts might provide more (or tidy up some of my info) @AdAstraEU

a nicer photo of the PR19

the under wing *twin* radiators and 4 blade prop tell you it's a Mk 9 on the left.