Blocklisting Application

GW Pharmaceuticals PLC ("GW Pharmaceuticals")

BLOCK LISTING APPLICATION

Porton Down, UK, 18 May 2011: GW Pharmaceuticals (AIM: GWP) hereby provides notification that application has today been made to the London Stock Exchange for admission to trading on AIM of two blocks of new ordinary shares of 0.1p each.

These new ordinary shares will be issued from time to time pursuant to the exercise of employee share options under the GW Pharmaceuticals share options schemes, as follows:

500,000 new ordinary shares for issue by the GW Pharmaceuticals Unapproved Share Option Scheme 2001.

300,000 new ordinary shares for issue by the GW Pharmaceuticals Executive Share Option Scheme.

On exercise the shares will be issued credited as fully paid and will rank pari passu with the existing ordinary shares in issue.

It is expected that such admission will become effective on 24 May 2011.

For further information, please contact:

GW Pharmaceuticals PLC +44 (0)1980 557 000

Adam George, Company Secretary

Peel Hunt LLP (Nominated Adviser)

James Steel/Vijay Barathan +44 (0) 20 7418 8900