I had a great swim this morning. After doing more drills for about 1200 meters, I could feel the results starting to gel.
During the last 300 meters or so of my workout it all suddenly fell into place. I could really feel the extra pull being generated by correct arm movements through the water. It was really a eureka kind of moment. I immediately felt faster, but I will have to wait till I get home to see what my Garmin has to say about the speed.
The real trick now will be to duplicate this movement in the pool from now on.