Holding(s) in Company

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARESi

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

GW Pharmaceuticals PLC

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

An acquisition or disposal of voting rights

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

X

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: iii

VHCP Management LLC ("Management")

Venrock Healthcare Capital Partners, L.P. ("VHCP")

Anders D. H. Hove ("Mr Hove")

Bryan E. Roberts ("Mr Roberts")

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

Citibank NA (as depository of GW Pharmaceuticals ADRs)

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

8 May 2013

6. Date on which issuer notified:

3 July 2013

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

Above 5%-- Management

Above 3%-- VHCP

8. Notified details: VHCP Management LLC

A: Voting rights attached to shares viii, ix

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 x

Direct

Direct xi

Indirect xii

Direct

Indirect

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate xiii

Exercise/Conversion Period xiv

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

% of votingrights

American Depository Receipts for GW Pharmaceutical shares

10,053,600

5.66%

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transaction

Type of financialinstrument

Exercise price

Expiration date xvii

Exercise/Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

10,053,600

5.66%

8. Notified details: Venrock Healthcare Capital Partners, L.P.

A: Voting rights attached to shares viii, ix

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 x

Direct

Direct xi

Indirect xii

Direct

Indirect

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate xiii

Exercise/Conversion Period xiv

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

% of votingrights

American Depository Receipts GW Pharmaceutical shares

8,498,916

4.79%

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transaction

Type of financialinstrument

Exercise price

Expiration date xvii

Exercise/Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

8,498,916

4.79%

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

Management exercises management/control over the assets of VHCP (which holds 708,243 ADRs representing 8,498,916 shares) and VHCP Co-investment Holdings LLC (which holds 129,557 ADRs representing 1,554,684 shares).

VHCP Co-investment Holdings LLC does not have a separately notifiable interest as the ADRs in which it is interested are convertible into less than 3% of the company's issued ordinary share capital.

Proxy Voting:

10. Name of the proxy holder:

N/A

11. Number of voting rights proxy holder will ceaseto hold:

N/A

12. Date on which proxy holder will cease to holdvoting rights:

N/A

13. Additional information:

N/A

14. Contact name:

John Heard

15. Contact telephone number:

0207 534 1500