As the season draws on, it can become harder to get tomatoes to ripen. The light levels are lower and the air tends to become moist, which can introduce more pests and diseases. I have always taken the secateurs to the leaves to keep thinning them out. I have always thought it a good policy to remove any crossing or compromised leaves to prevent diseases and to remove some leaves to raise light levels.
Ken Thompson, who is a plant biologist with a keen interest in the science of gardening, (and writes some really interesting stuff around gardening) has an article on the Telegraph about removing tomatoes leaves. Received wisdom has generally been to the effect that removing the lower, older leaves is good but research is now showing that when leaves were removed up to two trusses above the ripening truss, this meant the fruits were warmer and ripened earlier than those on plants where only lower leaves were removed, none of which had any effect on yield. The full article is very interesting and well worth a read.
Since I have always been quick to get out the secateurs around the tomato leaves, this gave me a good reason to go out into the greenhouse and chop away. I have denuded the tomato plants of all leaves up to the second truss, and left the young growth in tact. It will be interesting to see what happens, frankly this year, with the poor summer the tomato plants need all the help they can get. The image left shows how the plants now look.
If all else fails there is the sunday gardener fool proof way of ripening tomatoes at the end of the season.