Holding(s) in Company

1. Identity of the issuer or the underlying issuerof existing shares to which voting rights areattached:

GW PHARMACEUTICALS PLC

2 Reason for the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

ü

An acquisition or disposal of qualifying financial instruments which may result in the acquisition of shares already issued to which voting rights are attached

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments

An event changing the breakdown of voting rights

Other (please specify):

3. Full name of person(s) subject to thenotification obligation:

FMR LLC

4. Full name of shareholder(s)  (if different from 3.):

See Section 9

5. Date of the transaction and date onwhich the threshold is crossed orreached:

13th March 2015

6. Date on which issuer notified:

30th April 2015

7. Threshold(s) that is/are crossed orreached:

5%

8. Notified details:

A: Voting rights attached to shares

Class/type ofshares

if possible usingthe ISIN CODE

Situation previousto the triggeringtransaction

Resulting situation after the triggering transaction

NumberofShares

NumberofVotingRights

Numberof shares

Number of votingrights

% of voting rights

Indirect

Direct

Indirect

Direct

Indirect

GB0030544687

11,126,316

11,126,316

15,184,896

15,184,896

6.41%

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate

Exercise/Conversion Period

Number of votingrights that may beacquired if theinstrument isexercised/ converted.

% of votingrights

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Exercise price

Expiration date

Exercise/Conversion period

Number of voting rights instrument refers to

% of voting rights

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

15,184,896

6.41%

9. Chain of controlled undertakings through which the voting rights and/or thefinancial instruments are effectively held, if applicable: xxi

Proxy Voting:

10. Name of the proxy holder:

FMR LLC

11. Number of voting rights proxy holder will acquire:

4,058,580

12. Date on which proxy holder will acquire voting rights:

13th March 2015

13. Additional information:

None

14. Contact name:

Elizabeth Akande

15. Contact telephone number:

[email protected], 01737 837126