Exhibit 4.1

EXECUTION VERSION

WILLIS NORTH AMERICA INC.,

as Issuer

WILLIS TOWERS WATSON PUBLIC LIMITED COMPANY,

as Parent Guarantor

WILLIS NETHERLANDS HOLDINGS B.V.

WILLIS INVESTMENT UK HOLDINGS LIMITED

TA I LIMITED

TRINITY ACQUISITION PLC (f/k/a TRINITY ACQUISITION LIMITED) and

WILLIS GROUP LIMITED,

as Existing Guarantors

WILLIS TOWERS WATSON SUB HOLDINGS LIMITED and

WTW BERMUDA HOLDINGS LTD.,

as New Guarantors

and

THE BANK OF NEW YORK MELLON (as successor to JPMorgan Chase Bank, N.A.),

as Trustee

Seventh Supplemental Indenture

Dated as of March 9, 2016

to the

Indenture

Dated as of July 1, 2005

as amended and supplemented by the

First Supplemental Indenture,

Dated as of July 1, 2005,

Second Supplemental Indenture,

Dated as of March 28, 2007,

Third Supplemental Indenture,

Dated as of October 1, 2008,

Fourth Supplemental Indenture,

Dated as of September 29, 2009,

Fifth Supplemental Indenture,

Dated as of December 31, 2009,

and

Sixth Supplemental Indenture

Dated as of December 22, 2010

Providing for the Assumption of Guaranteed Obligations

EXECUTION VERSION

SEVENTH SUPPLEMENTAL INDENTURE

SEVENTH SUPPLEMENTAL INDENTURE (this “Seventh Supplemental Indenture”), dated as of March 9, 2016, among Willis North America, Inc., a Delaware corporation (the “Issuer”), Willis Towers Watson Public Limited Company (f/k/a Willis Group Holdings Public Limited Company), a company organized and existing under the laws of Ireland (the “Parent Guarantor”), the Guarantors listed on Schedule A, attached hereto (the “Existing Guarantors”), Willis Towers Watson Sub Holdings Limited, a company organized and existing under the laws of Ireland (“Willis Sub”), WTW Bermuda Holdings Ltd., a company incorporated under the laws of Bermuda (together with Willis Sub, the “New Guarantors”) and The Bank of New York Mellon (as successor to JPMorgan Chase Bank, N.A.) a New York banking corporation (the “Trustee”), to the Indenture, dated as of July 1, 2005, among the Issuer, the Parent Guarantor, the guarantors party thereto and the Trustee (the “Base Indenture”), as amended and supplemented by the First Supplemental Indenture, dated as of July 1, 2005 (the “First Supplemental Indenture”), the Second Supplemental Indenture, dated as of March 28, 2007 (the “Second Supplemental Indenture”), the Third Supplemental Indenture, dated as of October 1, 2008 (the “Third Supplemental Indenture”), the Fourth Supplemental Indenture, dated as of September 29, 2009 (the “Fourth Supplemental Indenture”), the Fifth Supplemental Indenture, dated as of December 31, 2009 (the “Fifth Supplemental Indenture”) and the Sixth Supplemental Indenture, dated as of December 22, 2010 (the “Sixth Supplemental Indenture” and together with the First, Second, Third, Fourth and Fifth Supplemental Indentures and the Base Indenture, the “Indenture”).

RECITALS:

WHEREAS, the Issuer, the Parent Guarantor, the Existing Guarantors and the Trustee have heretofore entered into the Indenture to provide for the issuance of the Issuer’s unsecured senior debentures, notes or other evidences of Indebtedness (the “Securities”);

WHEREAS, Section 10.01(9) of the Indenture permits the Issuer, the Guarantors and the Trustee without the consent of the Holders of the Securities to enter into a supplemental indenture to make any provisions with respect to matters arising under the Indenture, provided such action does not adversely affect the interests of the Holders of the Securities of any series in any material respect;

WHEREAS, each of the New Guarantors, wholly-owned subsidiaries of the Parent Guarantor, desires to assume all of the Guaranteed Obligations (this and other capitalized terms used herein and not otherwise defined have the meanings given to them in the Base Indenture) , including all obligations of a Guarantor under Article Sixteen of the Indenture;

WHEREAS, the Trustee has agreed to enter into this Seventh Supplemental Indenture to evidence the foregoing assumptions;

WHEREAS, the Trustee has received an Opinion of Counsel and an Officers’ Certificate, pursuant to Sections 1.02 and 10.03 of the Indenture, stating, as applicable, that (a) the execution of the Seventh Supplemental Indenture is authorized or permitted by the Indenture and (b) all conditions precedent provided for in the Indenture to such transaction and to the execution and delivery by the Trustee of the Seventh Supplemental Indenture have been complied with;

WHEREAS the Trustee has received a Board Resolution of the Issuer and a resolution of the board of directors of the Existing Guarantors and of the New Guarantors each authorizing the entering into of this Seventh Supplemental Indenture;

WHEREAS the Trustee is authorized to enter into this Seventh Supplemental Indenture and the Issuer has requested and hereby requests that the Trustee join with the Issuer, the Parent Guarantor, the Existing Guarantors and the New Guarantors in entering into this Seventh Supplemental Indenture; and

WHEREAS, all things necessary to make this Seventh Supplemental Indenture a valid agreement of the Issuer, the Parent Guarantor, the New Guarantors, the Existing Guarantors and the Trustee, in accordance with its terms, have been done.

NOW, THEREFORE, in consideration of the above premises, each party covenants and agrees, for the benefit of the other parties and for the equal and ratable benefit of all of the Holders of the Securities, as follows:

ARTICLE ONE

ASSUMPTION OF GUARANTOR OBLIGATIONS

Section 1.1 Assumption of Guarantor Obligations by Assuming Guarantors.

Each of the New Guarantors hereby assumes the Guaranteed Obligations of a Guarantor under the Indenture and the Securities, and thereby and hereby becomes, and agrees to be bound by all of the provisions of the Indenture (including Article Ten thereof) applicable to, a Guarantor (other than the Parent Guarantor), as if originally named as a guarantor in the Base Indenture; provided that notwithstanding anything contrary in Article 16 of the Indenture, the guarantees, obligations, liabilities and undertakings hereunder of any Guarantor incorporated under the laws of Ireland shall be deemed to be undertaken or incurred to the fullest extent permitted by law, except where the same would constitute unlawful financial assistance prohibited by Section 82 of the Companies Act 2014 of Ireland.

ARTICLE TWO

MISCELLANEOUS

Section 2.1 Integral Part.

This Seventh Supplemental Indenture constitutes an integral part of the Indenture.

Section 2.2 Adoption, Ratification and Confirmation.

The Indenture, as supplemented and amended by this Seventh Supplemental Indenture, is in all respects hereby adopted, ratified and confirmed, and this Seventh Supplemental Indenture shall be deemed part of the Indenture in the manner and to the extent herein and therein provided. The provisions of this Seventh Supplemental Indenture shall, subject to the terms hereof, supersede the provisions of the Indenture to the extent the Indenture is inconsistent herewith.

Section 2.3 Counterparts.

This Seventh Supplemental Indenture may be executed in any number of counterparts, each of which so executed shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument. The exchange of copies of this Seventh Supplemental Indenture and of signature pages by facsimile or PDF transmission shall constitute effective execution and delivery of this Seventh Supplemental Indenture as to the parties hereto and may be used in lieu of the original Supplemental Indenture for all purposes. Signatures of the parties hereto transmitted by facsimile or PDF shall be deemed to be their original signatures for all purposes.

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Section 2.4 Governing Law.

THIS SEVENTH SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS LAW. EACH OF THE ISSUER, THE PARENT GUARANTOR, THE EXISTING GUARANTORS, THE NEW GUARANTORS AND THE TRUSTEE IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS SEVENTH SUPPLEMENTAL INDENTURE OR THE TRANSACTIONS CONTEMPLATED HEREBY.

Section 2.5 Conflict with Trust Indenture Act.

If and to the extent that any provision of the Indenture or this Seventh Supplemental Indenture limits, qualifies or conflicts with a provision required under the terms of the Trust Indenture Act, the Trust Indenture Act provision shall control.

Section 2.6 Effect of Heading.

The Article and Section headings herein are for convenience only and shall not affect the construction hereof.

Section 2.7 Separability Clause.

In case any provision in the Indenture, this Seventh Supplemental Indenture or in the Securities shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

Section 2.8 Successors and Assigns.

All covenants and agreements in the Indenture and this Seventh Supplemental Indenture by the parties hereto shall bind their respective successors and assigns, whether so expressed or not.

Section 2.9 Benefit of Indenture.

Nothing in the Indenture or this Seventh Supplemental Indenture or in the Securities, express or implied, shall give to any Person, other than the parties hereto, any Security Registrar, any Paying Agent, and their successors hereunder, and the Holders of the Securities, any benefit or any legal or equitable right, remedy or claim hereunder or under the Indenture.

Section 2.10 The Trustee.

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or, sufficiency or adequacy of this Seventh Supplemental Indenture or for or in respect of the statements or recitals contained herein, all of which are made solely by the Issuer, the New Guarantors, the Parent Guarantor and the Existing Guarantors and the Trustee assumes no responsibility for their correctness.

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IN WITNESS WHEREOF, the parties hereto have caused this Seventh Supplemental Indenture to be duly executed, all as of the day and year first written above.

SCHEDULE A

EXISTING GUARANTORS

A-1