A useful article for A Level Economics relating to protectionism / protectionist policies – http://www.bbc.co.uk/news/world-us-canada-43337951 
See where to find this section within the specs for Edexcel, AQA and OCR:-
Edexcel spec reference 4.1.6 Impact of protectionist policies on consumers, producers, governments, living standards, equality.
AQA spec reference The causes and consequences of countries adopting protectionist policies. 
OCR spec reference P 25 Explain the impact of methods of protectionism to include a diagrammatic explanation of tariffs and quotas.