Complex sentence: Organised by the WWF and the Scout Association, It lasts for one week and 2 days in March every year, in 2006 it was from the 18th to the 26th March.
Split into simpler sentences: Organised by the WWF and The Scout Association, it lasts for 9 days in March every year. In 2006, it occurred from the 18th to the 26th March.