Clearly, it depends.
As drauk suggests, if one sticks to short local flights on nice days, then currency is much less important than if one is doing serious flights in real English weather.
An awful lot of GA pilots, the big majority I think, do exactly the former type of flying: short local flights and sticking to nice days. I gather the UK PPL average is somewhere around 10-20hrs/year so there are a lot of people who fly very little.
It doesn't take much to fly a simple plane on a nice day, along the coast and back. Just make sure you stick to the checklist, to make sure nothing has been forgotten.
Personally, I need to be fully current for VFR and IFR and I go up at least once a week no matter what, for a 1hr local flight on which I do various stuff including drilling holes in clouds, and if possible land with an instrument approach. And check out all the kit including the autopilot modes. But then nobody else is flying this plane and you can't leave an engine unused for weeks without getting internal corrosion. That said, in the current weather it is very difficult to get up at all, unless one is based on an airport with an ILS. Together with some long trips into the further corners of Europe, I manage to clock up about 150hrs/year and I regard that figure as my absolute minimum.