Come you lot, pagan's all. The solstice is the longest day. The sun rises at it's earliest and sets at it's latest.Mid summers day is June 24th.

Don't forget that there have been climate changes since the solstice days and equinoxes were worked out. Take for instance frost fairs that happened before the winter solstice, when rivers were frozen and winter had a good grip. now a days, the winter though not as cold is only just begining to grip in the UK

One explanation for mid summers day being only 3 days after the solstice is that our summers are so bloody horrible that by a week later it's raining again and so summer happens within a week (joke)