A second referendum that reverses Brexit would have a "positive" and "significant" impact on the UK economy, a leading think tank has claimed.

The Organisation for Economic Co-operation and Development has projected that the British economy will grow by just 1 per cent next year in part because of uncertainty around Brexit.

It said that there is a risk of a "disorderly" Brexit, in which the UK leaves without a deal triggering an "adverse reaction" in the financial markets and pushing exchange rates to new lows.

The head of the OECD is unveiling the report at a press conference alongside Philip Hammond, the Chancellor, in the Treasury. Mr Hammond has faced repeated criticism for being "gloomy" about Brexit.

The OECD report says: "In case Brexit gets reversed by political decision (change of majority, new referendum, etc.), the positive impact on growth would be significant."