Historical re-enactment has a unique position as probably the most varied hobby in the world!
The common theme seems to be the way in which re-enactors put aside their everyday lives as they immerse themselves in the re-enactment water. In many cases, re-enactors will tell you they do not actually know what are the 'real life' occupations of their fellow participants. On a personal level, this is one of the great attractions of re-enactment; that an individual's worth is measured by their skills and abilities rather than their wealth, class or occupation.
In this context, the closest friendships are struck more quickly and deeply than in many other areas of our modern lives.
With this outlet from hum-drum life, the re-enactor has a unique freedom to roam the centuries - to explore the intricacies of our ancestors minds and habits. Thus, for the individual or the family, re-enactment allows a unique exploration of life, unconstrained by the present.
For those outside re-enactment, there is something very valuable to be gained. Most re-enactors are members of organisations that put on educational or entertaining displays for the public. So, while re-enactment is an enjoyable hobby for individuals, it is in putting on re-creations of historical life that they find their wider purpose.
When re-enactors are working at their peak as a team, when they have found the perfect theme to sink themselves into, watching them at work is an absorbing experience. However, when the excitement and adrenaline that they are generating spills over, they have the power to draw the audience right into the centre of their imagining.
For a history of re-enactment in the UK, see Howard Giles' (from EventPlan Ltd) excellent article here