It really does sound as though your choke were not engaging at all. You've verified that all is well under the dash. Next step is to go to the carb end of that cable and verify that the cable's not broken or loose or hanging up somewhere at the carb. The cold start devices are pretty reliable but it's always worth checking, first, that the cable is in fact operating the device. It's not unusual for cold start devices to be deliberately disabled in not-so-cold climates; the car will still start most of the time with nothing more than a kick on the gas while the engine turns.

If the device is working then you need to sort out the mixture -- there are video tutorials online explaining how to set up your SUs, so make sure your ignition and valves are set right, spend some time on YouTube, and have at! Tutorials made for British cars are also applicable to Volvo.