How much time in the UK to get extension?

[FromOZ]

Hi all

I'm here on HSMP (still in my first year), and travel to Europe fairly regularly for work/holidays.

I've seen mention in these forums that to get a renewal you need to be in the UK for a minimum time. Does anyone know exactly what that time is, and where I can find it from the official website? All I can find there is that to get settlement after four years, you can only have been outside the UK for not more than 6 months.

Any guidance would be much appreciated.

FromOZ