This study will be a multi-centre, randomised, double-blind, placebo-controlled, parallel-group pilot study. There will be two parallel groups of participants (0mg-250mg GWP42003 and placebo, twice daily), with a treatment duration of 10 weeks as well as a 7 day baseline period and one week follow-up. The two treatment groups of 0mg-250mg GWP42003 and placebo will be randomised equally into a 1:1 ratio, with 31 participants in the active IMP group and 31 participants allocated placebo treatment.