Billy Caldwell has left hospital after his cannabis oil was returned following protests by his mother, Charlotte

A panel of experts led by the chief medical officer will advise the government on issuing licences for medical cannabis, it was announced today.

The panel, which will be chaired by Professor Dame Sally Davies, will look at applications to use the drug on a case-by-case basis to make the process more “clinically led”.

It came as it emerged that Billy Caldwell, the 12-year-old boy who had his medical cannabis oil confiscated by the Home Office last week, had left hospital after his condition had improved following the return of the drug.

Answering an urgent question on the issue in parliament, Nick Hurd, the home office minister, also signalled that the government would conduct a more detailed review of medical marijuana.

He said: “As