Yvonne's Mystery Tree

Three-year-old evergreen tree is about a metre and a half high. Mostly just one stem, but some branches near bottom. Leaves are not in pairs. Leaves are smooth and have smooth edges. Biggest leaf is maybe 120mm long, not including stem. The owner can't remember whether she bought it or it's a self-sow. Nothing similar in neighbouring gardens, so most likely bought. It's in a pot.