The idea of left wing politicians is so much part of the furniture that I'd not thought about how the term is derived, seems that it dates back to the French Revolution where in National Assembly the aristocracy supporters were on the right and the commoners on the left.
Historically the left is considered progressive and the right somewhat reactionary but there have been many 'radical' conservatives of late trying to roll back the areas of influence of the state.
In fact some contemporary commentators consider that the extremes on both the left and right can share more in the beliefs than those in the centre.
The media often finds it easy to position individuals and parties in the spectrum from Left to Right but increasingly new trends and affinities are confusing the picture where many modern conservatives are considered 'liberal' on personal issues but 'conservative' financially.
The diagram shows a more nuanced interpretation of the parties active in the UK.
The green movement is generally considered to find a place somewhere on the left.