Alison Garnham is Chief Executive of Child Poverty Action Group Food banks have become a political football. Some say demand is driven by supply: if you build it, they will come. Others point to the rising cost of living, especially food price inflation, or benefit cuts as the key drivers of demand (or need). Yet, with the notable exception of a long-suppressed report for Defra, and regular figures on food bank use from the Trussell Trust, in-depth evidence on reasons…