937 Spit XIVs were built, Source "Spitfire in Action" page 39 Squadron Signal.
In the ETO the following Spit XIV Sqn were operational in the ETO by *November 1944* with the 2nd Allied Tactical Air Force on the Continent: Nos 610, 91, 322, 41, 130, 350, 403, 2 (8 Squadrons). Source "Late Marque Spitfire Aces" Opsrey, pages 32-33. More were added by wars end (Milos post looks accurate to me), and 37 RAF Sqns eventually flew they type. Source "Spitfire in Action" page 39, Squadron Signal.
Along with the Hawker Tempest they formed the backbone of the RAFs air superiority fighters in Europe. Source "Late Marque Spitfire Aces" Opsrey, page 33.
You can verify the above in your own time, there are any # of credible sources for Spit XIV squads at wars end, and for the #s at varying stages.
*As for #s of operational 109K-4s flown during the war, somebody else can find that data. I have seen quotes on what units used "some" of them without any strengths given. This is mainly due to the difficulty of finding info on the LW in the last 6 months of the war.*
"So no reference, no source, just the usual incoherent hysteria."
-Indeed?
As for the 109K-4 itself (and the 109G-10), they were, by all accounts, the pinnacle of fighter design, and their performance is a reflection of that. They certainly were on par with anything in the world in 1945 from the data I have seen?, both in terms of speed and climb rate. I cant recall anybody credible claiming otherwise (including authors on Spitfire books). If you want to endlessly bicker over +/- 10 mph at a given alt, fuel type, boost pressure, go ahead...