Sir Patrick Stewart has given his support to the campaign for a young boy to be given medicinal cannabis to treat his epilepsy.
Alfie Dingley, aged six, suffers from a rare condition and can have up to 150 potentially life-threatening seizures a month.
He has been in hospital three times since returning from Holland four weeks ago, where his symptoms improved after he was treated with cannabis oil.
His parents, Drew Dingley and Hannah Deacon, want the Government to let him use the medication, a banned substance in the UK.
Sir Patrick, who uses medicinal cannabis to treat his arthritis while living in California, met Alfie and his family and gave his support to the campaign.
He said: “How could one not support Alfie?
“Hearing what his life has been and the benefits given to him by being able to use medicinal marijuana.
“There has never been a stronger case for the legalisation of medical marijuana.
“I have been registered for medical marijuana in California for over three years and have found it immensely beneficial for my arthritis.
“I had to have eight steroid injections in my fingers and knuckles, which was about as painful as anything one could imagine, because medicinal cannabis is not available here.”
Alfie and his parents, from Kenilworth in Warwickshire, will hand the 380,000-strong petition to Number 10 Downing Street on Tuesday.
Mr Dingley said: “Alfie’s condition is worsening, which is obviously a worry.
“The steroids have side effects, they make people more aggressive and we’ve seen a change in his behaviour.
“We just want our little boy back, our happy little six-year-old playing with his sister.”
He added: “This is our six-year-old son, we’re not going to put something into him that’s in any way illegal.
“What we’re asking for is a medical grade product, made under laboratory conditions, which is bottled and prescribed in the way any pain killer is.
“It’s amazing the support we’ve had, Richard Branson came out of the blue and all the support has been amazing from people.
“Hopefully things are starting to move in the right direction.”
Ms Deacon said: “Alfie is really struggling and really suffering.
“The longer this goes on the longer he will suffer and it has to stop.”
She added: “It’s really important that the Government understands the importance of feeling in the public domain, we have a lot of public support.
“We’re hoping to get some reassurance and clarity on what the Government will do to help us.”
A number of other high-profile figures have backed the campaign, including Joanna Lumley and Sir Richard Branson.