Under the Securities Exchange Act of 1934
(Amendment No. 12)*

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. o

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(1) All Common Shares held by Cascade Investment, L.L.C. (“Cascade”) may be deemed to be beneficially owned by William H. Gates III as the sole member of Cascade.

(2) Based on 29,152,821 Common Shares outstanding as of June 30, 2014 as reported on the Issuer’s Form N-CSRS filed on August 25, 2014.

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(1) All Common Shares held by Cascade Investment, L.L.C. (“Cascade”) may be deemed to be beneficially owned by William H. Gates III as the sole member of Cascade.

(2) Based on 29,152,821 Common Shares outstanding as of June 30, 2014 as reported on the Issuer’s Form N-CSRS filed on August 25, 2014.

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EXPLANATORY NOTE

This Amendment No. 12 to Schedule 13D (“Amendment”) relates to the Common Shares of Beneficial Interest without par value (the “Common Shares”) of Western Asset/Claymore Inflation-Linked Securities & Income Fund (the “Issuer”).  This Amendment is filed to amend and supplement the Items set forth below of the Reporting Persons’ Schedule 13D previously filed with the Securities and Exchange Commission on January 3, 2006, as amended on April 19, 2006, June 19, 2008, July 7, 2008, July 17, 2008, October 17, 2008, October 15, 2010, September 12, 2012, April 21, 2014, December 12, 2014, December 15, 2014, and December 24, 2014.

Item 3.                   Source and Amount of Funds or Other Consideration

Since the event requiring its most recent Schedule 13D filing, Cascade purchased 516,547 Common Shares with its working capital for an aggregate purchase price of $6,051,540.57.  Cascade also acquired 15,056 Common Shares pursuant to a dividend reinvestment plan of the Issuer. Other than the reinvestment of the dividends, Cascade paid no consideration to acquire these shares.

Item 5.                   Interest in Securities of Issuer

(a)  See items 11 and 13 of the cover pages to this Schedule 13D for the aggregate number of shares and percentage of Common Shares beneficially owned by each of the Reporting Persons.

(b)  See items 7 through 10 of the cover pages to this Schedule 13D for the number of Common Shares beneficially owned by each of the Reporting Persons as to which there is sole power to vote or to direct the vote, shared power to vote or to direct the vote and sole or shared power to dispose or to direct the disposition.

(c) During the December 23, 2014 through January 15, 2015, Cascade purchased 516,547 Common Shares for cash in open market transactions and acquired 15,056 Common Shares pursuant to a dividend reinvestment plan of the Issuer, in each case on the dates and at the price per share set forth on Exhibit 99.1, which is attached hereto and incorporated herein by reference.

(d)  None.

(e)  Not applicable.

Item 7.                   Materials to be Filed as Exhibits

Exhibit 99.1                              Transactions by Cascade

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

(1) This Amendment is being filed jointly by the Reporting Persons pursuant to the Joint Filing Agreement dated January 3, 2006 and included with the signature page to the Reporting Persons’ Schedule 13D with respect to the Issuer filed on January 3, 2006, SEC File No. 005-77986, and incorporated by reference herein.

(2) Duly authorized under Special Limited Power of Attorney appointing Alan Heuberger attorney-in-fact, dated October 11, 2013, by and on behalf of Michael Larson, filed as Exhibit 99.1 to Amendment No. 12 to Cascade’s Schedule 13D with respect to Western Asset/Claymore Inflation-Linked Opportunities & Income Fund on December 11, 2013, SEC File No. 005-81261, and incorporated by reference herein

(3) Duly authorized under Special Limited Power of Attorney appointing Alan Heuberger attorney-in-fact, dated August 12, 2008, by and on behalf of William H. Gates III, filed as Exhibit 99.2 to Amendment No. 1 to Cascade’s Schedule 13D with respect to Otter Tail Corporation on April 15, 2009, SEC File No. 005-06638, and incorporated by reference herein.

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