By Andy Lines More than 300,000 people have now fled the city of Rafah as UK politicians called for Israel to show restraint in its onslaught on Gaza. Foreign Secretary David Cameron urged Israel not to launch an offensive on the southern city without a clear plan to ensure refugees were safe and had access to food and medicine. But he warned that simply changing Britain’s policy on arms sales to Israel would “make Hamas stronger”. Israeli Prime Minister Benjamin Netanyahu has repeatedly vowed to launch a full ground invasion of Rafah. Lord Cameron said: “For there to be a major offensive in R…