Years ago, there was a gardening program on the TV with a chap called James Stirling. He advised picking the flowers off of strawberry plants up until Labour Weekend to improve the health of the plant and to improve yields. Is there any logic in this? My Dad did it for years and we got a lot of small strawberries, bearing in mind I don't think we had the hybrid cultivars available today that give better crops.

There is some logic in this.

• Early in the season fruit is often not properly pollinated by bees due to wet windy weather and so fruit becomes misshapen.
• It is a good idea to pick the misshapen fruit off the plants so that the plants energies go into establishing a good strong root system.
• As temperatures warm up more flowers will appear with a better chance of complete pollination by bees.
• Plants that are kept for several seasons will have progressively smaller fruit; each season take new plant runners to ensure a continuous supply of larger juicier fruit.
• If fruit sets early the plants energies go into producing the fruit rather than establishing their root system which will sustain fruiting throughout the growing  season.
• You are correct in saying that there are improved varieties with higher yields and larger juicier fruit available to the home gardener now.
• Regular feeding of your strawberry plants will improve fruit size and flavour, liquid feed with Tui Strawberry Superfood weekly or apply Tui Strawberry food every 4-6 weeks to plants in garden beds as they do a lot of growing in a short space of time, you might even get a small autumn crop as well.