Well I have a Mk I, or at least the mostly white Pro, with a 1970 serial number, even though it corresponds to the 1969 catalog. The catalogs show the 1970 Mk II with the fastback stays, and different geometry. Perhaps they built some Mk I's in 1970 to use up the older tubesets, much as Schwinn built the early 80's Superior to use up leftover Paramount tubesets. Or maybe they had some delay in rolling out the Mk II in 1970, so continued the Mk I until the Mk II was in production.
BTW, did any of Pros after the Mk I and before the Team Pro have conventional seatstays, as opposed to the Brampton fastback stays? I could have sworn I'd seen early 70's Pros in the mink brown color with conventional stays, but the 1970 catalog at RetroRaleighs shows the 1970 Mk II already with the Brampton stays. There is no 1971 catalog there, so no photo of the MK III, but the 1972 catalog shows the MK IV with Bramption stays (best as I can make out). I suppose they might have gone to Brampton stays on the Mk II, then back to conventional on the MK III, then back to Brampton again on the MK IV. But that would be very strange, even for Raleigh.
Big Spring, Texas, USA
> From: donald gillies <firstname.lastname@example.org>
\r?\n> Subject: Re: [CR] Raleigh Professional Mark IV--high BB
\r?\n> To: email@example.com
\r?\n> Cc: firstname.lastname@example.org
\r?\n> Date: Tuesday, February 24, 2009, 7:24 PM
\r?\n> The Raleigh Pro's indeed have very short top-tubes. I
\r?\n> have a feeling
\r?\n> that's because they were supplied with longer stems
\r?\n> than you usually
\r?\n> see on a racing frameset, perhaps to make the italianesque
\r?\n> short-wheelbase design more stable to steer.
\r?\n> By the way, the Carlton Giro D'Italia - which is the
\r?\n> basis for the
\r?\n> Mark II, III, and IV models - is a very old model, going
\r?\n> back to the
\r?\n> early 1960's. In the late 1960s when Raleigh began
\r?\n> importing bikes
\r?\n> into the USA, I think the first model they imported was the
\r?\n> top-of-the-line Carlton Flyer, which was badged as a
\r?\n> Professional and
\r?\n> later retitled "Professional Mark I".
\r?\n> I am wondering what is the difference between a
\r?\n> Professional Mark II,
\r?\n> III, and IV because they all appear to be similar to the
\r?\n> Giro D'Italia
\r?\n> in the Carlton Catalogues. What were they were tweaking in
\r?\n> 1971 and
\r?\n> Incidentally, I doubt that anyone owns a 1970 Mark I.
\r?\n> Beause that
\r?\n> would mean that in 1971, the Mark II AND the Mark III were
\r?\n> released in the same year!
\r?\n> - Don Gillies
\r?\n> San Diego, CA, USA