I did another 30 minute session on the treadmill. One bit quicker than last time. The 30 mins was broken up as follows:

5 min at 4.1 kph
2 min at 4.6 - Up 0.1 kph
3 min at 4.1
1 min at 4.5
4 min at 4.1
1 min at 4.5
4 min at 4.1
1 min at 4.5
4 min at 4.1
5 min at 3.5
I wore my heart monitor and it said I had an average heart rate of 120 bpm, was above 112 bpm for 26.26 minutes and used 193 calories.

As this was slightly less than last time it seems to indicate that my stamina is slowly improving. It will be interested to see what happens next time, this weekend.