Complex sentence: Although Labour was the largest party by councillor the Conservatives formed a coalition with councillors from the independent Isleworth Community Group (ICG) which administered the area until the 2010 local elections when all seven independent councillors lost their seats.
Split into simpler sentences: Although Labour was the largest party on the Council the Conservatives were able to form a coalition with councillors from the independent Isleworth Community Group (ICG). This lasted until the 2010 local elections when all the independent councillors lost their seats.