The male Migrant Hawker (shown here) is brown and blue with a few yellow/green patches on its thorax. Southern Hawkers are similar, but are a brighter blue and green. This was actually the first dragonfly I had seen in 5 years visiting Lindisfarne, it was flying near the path up to the Heugh by the Priory. They appear quite late in the year - August to October (one of the last dragonflies to appear). Females are brown and yellow (like many female dragonflies).