A few years back, I couldn’t step outside my front door in north London without hearing Polish spoken. Those were the boom years for the economy, pre-recession, when 500,000 Polish nationals came here to work.The emigrés whose work features in “Pole Position: Polish Art in Britain 1939-89” at the Graves Gallery, Sheffield (until 28 June) came here under rather different circumstances. The 19 artists in this show of 60 works from the private collection of Matthew Bateson arrived during or after the war as refugees rather than economic migrants. Their backstories are remarkably similar: most trained in Poland, continued their studies in Paris, served with the Polish forces in France, were captured and imprisoned and eventually found refuge in Britain, many gravitati