Hi Cromagnonman,
interesting link!
I asked IWC Concierge Services for more information and this is what they told me about the cal 70. (very interesting!)
"we are pleased to provide you with a little bit of the History that our Experts in the Heritage Department have found about the Calibre 70:
"The movement was developed by the design team around Albert Pellaton. IWC constructed a valid movement at only a cost of 75% of what the Cal. 89 cost, namely the so-called "Economique - Kaliber 70".The movement had a small second at six o'clock, a rate of 18,000 beats per hour (2.5 Hz). The workpieces were identical to those of cal. 88, except that they had a flat spiral.
From the model, (Cal.70-12'"H3,8), which IWC produced only in the years 1945-1946, almost 4,800 movements had been manufactured.That with a little second equipped manual wind movement was the first men's wristwatch with flat spiral at IWC.During the phase of research and development, however, different limits, such as restrictive pricing and import regulations, had been imposed to IWC. In order to protect the Swiss Watch Association, new price limits and import regulations had been established. Thus, IWC had stopped the production of the Calibre 70 immediately, as its price and production costs were below the new imposed standards.[i]The cal. 70 is only a marginalia of the company's history from IWC, but it clearly shows that under Albert Pellaton the construction of watch movements was taken to keep the cost structure of the movement low.
The innovative idea, due to the socio-economic conditions immediately after World War II and the will to develop, a solid, high quality clockwork were undermined by external factors. This is a very good example of the influence of structural conditions and the latent certainty that an innovative project is brought to failure."
[/i]
The above is a translation from an original document in German."