Last year I could not understand why we were not seeing these 2 insects until June. After some research and 3 early morning visits to Ramsley, I now have the answer!
Both large reds and 4 spotted chasers are emerging during the second half of May, but straight away they leave the water's edge and fly off to mature in the nearby woodland. They do not return to the water until they are ready to fight and breed. In fact some insects may travel several miles, searching out new habitats. In this way the population gets crossed with other breeding colonies, ensuring the strength of the gene pool.
The first water's edge sightings may therefore not be until June. It is somewhat galling that we are up to 2 months behind the South of England and therefore have a somewhat shorter dragonfly and damselfly season.
Here is a link to my more detailed article and photographs of the damselfly emergence.
Below is a photograph of a 4 spotted chaser just after emergence, and its exuvia (the final cast skin).