an associate degree was called a diploma in the UK. It allowed you to enter industry as a technician. You could join a technical/professional group as an associate member. With experience and more study you could work your way up both in the firm and in the professional group.
With a Bachelor's degree you could join as an officer. Your grounding in the chosen field was deeper, and you could expect to be given new problems to solve, not repetitive work. That allowed you a faster promotion and more responsibilities sooner. You could get to the Board.
With time, a Bachelor's wasn't sufficient. You needed a Masters, and with more sophistication, you now needed courses in Business Administration to go beyond a certain point in your career, unless you wanted to stay a specialist in your field. In that case, big companies provided a professional career path parallel to management.
If you did a PhD, your chances of employment in the British Industry went down. In Europe, and the US, your chances were better, if you could demonstrate a command over the subject (which had to relevant to your employer's field of business), and if you could also provide evidence of leadership.