X0306 4 2020-06-15 0 0001351288 GW PHARMACEUTICALS PLC GWPH 0001754129 Gover Justin D. SOVEREIGN HOUSE, VISION PARK, HISTON CAMBRIDGE X0 CB24 9BZ UNITED KINGDOM 1 1 0 0 Chief Executive Officer Ordinary Shares 2020-06-15 4 M 0 4164 0.0013 A 458129 D Ordinary Shares 2020-06-15 4 F 0 2076 10.23 D 456053 D Stock Options 0.0013 2020-06-15 4 M 0 4164 0.00 D 2020-06-15 2020-06-15 Ordinary Shares 4164 0 D Exercise of stock options. Following the exercise, these shares were converted into American Depositary Shares ("ADS") of the Issuer. Each ADS represents twelve ordinary shares of the Issuer. Converted from British Pounds Sterling to U.S. Dollars using currency ratio of 1.00 British Pound Sterling = 1.25 U.S. Dollars as of June 15, 2020. Column 5 of Table I of the reporting person's form 4 filed with the SEC on March 4, 2020 includes 112,548 ordinary shares underlying RSU style share options pursuant to the Issuer's Long-Term Incentive Plan, including (i) 44,880 ordinary shares vesting automatically in two equal installments on February 26, 2021 and 2022, (ii) 51,012 ordinary shares vesting automatically in three equal installments on March 1, 2021, 2022, and 2023, and (iii) 16,656 ordinary shares vesting automatically in four equal installments on June 14, 2020, 2021, 2022, and 2023. These ordinary shares have been excluded from Column 5 of this form 4 and will be reported as each tranche is vested and automatically exercised. Mandatory withhold to cover vested RSU style share options. Represented by ADS. The price reported is price per ordinary share converted from price per ADS. /s/ Justin D. Gover 2020-06-17