Exhibit 99.1
                 Important Notice Concerning Limitations on Your
               Trading in Willis Group Holdings Limited Securities
                         During Special Blackout Period
                         ------------------------------



                                                                December 1, 2008

To:      Directors and Executive Officers of Willis Group Holdings Limited
         ("Willis")

From:  Adam G. Ciongoli


Summary. This notice is to inform you of significant restrictions on your
ability to deal in Willis common shares as well as derivative  securities,  such
as stock options,  during an upcoming  "special"  blackout period.  As described
more fully below,  this  blackout  period for Willis'  directors  and  executive
officers is expected  to commence at 4:00 pm Eastern  time on Tuesday,  December
30, 2008 and to end during the week of January 4, 2009.  This blackout period is
in addition to the customary dealing blackout periods preceding Willis' earnings
releases. It is imposed on all directors and executive officers of Willis by the
Sarbanes-Oxley  Act  of  2002  and  U.S.   Securities  and  Exchange  Commission
Regulation BTR (Blackout  Trading  Restriction).  As more fully described below,
during this blackout  period you will  generally be prohibited  from engaging in
transactions  involving Willis equity securities (including common shares, stock
options and other  derivatives).  We will notify you of any changes  that affect
the dates of the blackout period.

1.   The blackout  period is being imposed in connection  with the merger of the
     HRH  Retirement  Savings  Plan  (the "HRH  Plan")  into the  Willis  401(k)
     Retirement  Savings  Plan  effective  January  1, 2009 (the  "Merger").  In
     connection  with the Merger,  a "blackout  period" for the HRH Plan will be
     imposed and participants will be unable to direct or diversify  investments
     or obtain a loan or distribution from the HRH Plan ("HRH blackout period").
     The HRH blackout  period is necessary for the HRH Plan's trustee to process
     and implement the Merger.  Since the HRH blackout  period may last for more
     than three business days,  there must be a  corresponding  blackout  period
     applicable  to directors  and  executive  officers of Willis.  Accordingly,
     Willis directors and executive  officers will be generally  prohibited from
     engaging in transactions  involving  Willis equity  securities  acquired in
     connection with their service to Willis.

2.   The HRH blackout period is expected to begin at 4:00 p.m., Eastern Time, on
     December  30,  2008,  and end during  the week of January 4, 2009.  We will
     notify you of any changes that affect the dates of the HRH blackout period.
     In  addition,  you can  confirm  the status of the HRH  blackout  period by
     contacting  Shaun  Bryant at +44 (0)20 3124 7146 or by calling  Diversified
     Investment Advisors, toll-free at 1-800-755-5801.

3.   As a result of the Merger, during the HRH blackout period,  participants in
     the  HRH  Plan  will be  temporarily  unable  to (1)  direct  or  diversify
     investments in their individual account, (2) take distributions  (including
     final  distributions) of money invested in the HRH Plan, and (3) take loans
     of money under the HRH Plan.


                                       5


4.   Generally,  during the HRH blackout  period,  you will be  prohibited  from
     directly or indirectly,  purchasing,  selling or otherwise transferring any
     equity security of Willis that you acquired in connection with your service
     as a director or an  executive  officer.  "Equity  securities"  are defined
     broadly  to  include   stock   options  and  other   derivatives.   Covered
     transactions are not limited to those involving your direct ownership,  but
     also  include  any  transaction  in which  you have a  direct  or  indirect
     pecuniary interest.  For example,  you may be deemed to have an interest in
     transactions in equity  securities of Willis by your family members if such
     securities  were  originally  acquired in  connection  with your service or
     employment as a Willis executive officer or director.

5.   The prohibition covers securities acquired "in connection with service as a
     director or employment as an executive officer." This includes, among other
     things,  securities  acquired by you under a compensatory  plan or contract
     (such  as  under  a  stock  option  or a  restricted  stock  grant),  as an
     inducement  to your  employment  or  joining  the  Board of  Directors,  in
     transactions  between you and Willis,  and as shares  necessary  for you to
     qualify  as a director  or to satisfy  minimum  ownership  requirements  or
     guidelines.  Securities  acquired  outside of your service as a director or
     executive  officer  (such as shares  acquired when you were an employee but
     not yet an executive officer) are not covered.

6.   If you  engage in a  transaction  that  violates  these  rules,  you can be
     required to disgorge your profits from the transaction, and you are subject
     to civil and criminal penalties.

The rules summarized above are complex, and the criminal and civil penalties
that could be imposed upon directors and executive officers who violate them
could be severe. We therefore request that you contact Shaun Bryant at +44 (0)20
3124 7146 before engaging in any transaction involving Willis securities during
the HRH blackout period, or if you believe that any such transaction in which
you have a pecuniary interest may occur during the HRH blackout period.


                                       6