Keith, an interesting text for you to read would be the public consultation process of DDC leading up to the core strategy, a process which, if I'm not mistaken, took place around 2008.
You will find it somewhere on the DDC website. It's quite long and substantial, but in a nutshell it explains why the Council decided to adopt a core strategy envisaging the building of so many houses. One reason given was a presumed Pfizer expansion, and another was the supposed imminent creation of 4,000 jobs in the Dover area.
It doesn't exactly explain what jobs these would be, whether job-agency employment at salad factories or 3 month shifts at the Fancy Box, but at least you will find that the ultimate decision came from the Council.
Then there is the complicated thing about Growth Point Status, of which there is an article on Chris' other forum (see drop box), which, even though it says "Alexander", wasn't written by me, only commented on
Now back to the Port...