UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G
(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1(b) (c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13-d-2(b)

x

Rule 13d-1(b)

x

Rule 13d-1(c)

o

Rule 13d-1(d)

CUSIP No. 45768S105

1.

Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only)
White Mountains Insurance Group, Ltd. “White Mountains” (No. 94-2708455)

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

x

3.

SEC Use Only

4.

Citizenship or Place of Organization
Bermuda

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
0

6.

Shared Voting Power
563,200*

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
563,200*

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
563,200*

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
4.8%

12.

Type of Reporting Person (See Instructions)
HC,CO

CUSIP No. 45768S105

1.

Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only)
White Mountains Advisors, LLC. “WM Advisors” (No. 04-6140276)

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

x

3.

SEC Use Only

4.

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
0

6.

Shared Voting Power
224,000**

7.

Sole Dispositive Power
0

8.

Shared Dispositive Power
224,000**

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
224,000**

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
1.9%

12.

Type of Reporting Person (See Instructions)
IA,CO

Item 1.

(a)

Name of Issuer
Innospec Inc.

(b)

Address of Issuer’s Principal Executive Offices
Innospec Manufacturing Park
P.O. Box 17
Ellesmere Port
Cheshire, CH65 4HF
United Kingdom

Item 2.

(a)

Name of Person Filing
This statement is being filed by White Mountains Insurance Group, Ltd., a Bermuda corporation (“White Mountains”), and its wholly-owned subsidiary White Mountains Advisors, LLC, (“WM Advisors”), a Delaware corporation.  White Mountains is a property and casualty insurance holding company and WM Advisors is a registered investment adviser.

(b)

Address of Principal Business Office or, if none, Residence
The address of the principal executive office of White Mountains is 80 South Main Street, Hanover, NH 03755.  The address of the principal executive office of WM Advisors is 370 Church Street, Guilford, CT 06437.

(c)

Citizenship

(d)

Title of Class of Securities
Common Stock

(e)

CUSIP Number
45768S105

Item 3.

If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

o

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).

(b)

o

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

(c)

o

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).

(d)

o

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C 80a-8).

(e)(1)

x

An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)

o

An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)(2)

x

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

o

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

o

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

o

Group, in accordance with §240.13d-1(b)(1)(ii)(J).

Item 4.

Ownership

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

Name of Reporting Persons: White Mountains (No. 94-2708455)

(a)

Amount beneficially owned:    563,200 shares

(b)

Percent of class:    4.8%

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote    0

(ii)

Shared power to vote or to direct the vote     563,200***

(iii)

Sole power to dispose or to direct the disposition of    0

(iv)

Shared power to dispose or to direct the disposition of    563,200***

Name of Reporting Persons: WM Advisors (No. 04-6140276)

(a)

Amount benefically owned:   224,000 shares.

(b)

Percent of class:    1.9%

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote    0

(ii)

Shared power to vote or to direct the vote     224,000***

(iii)

Sole power to dispose or to direct the disposition of    0

(iv)

Shared power to dispose or to direct the disposition of    224,000***

Item 5.

Ownership of Five Percent or Less of a Class.

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following   x

Item 6.

Ownership of More than Five Percent on Behalf of Another Person

Not applicable

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person

Not applicable

Item 8.

Identification and Classification of Members of the Group

Not applicable

Item 9.

Notice of Dissolution of Group

Not applicable

Item 10.

Certification

WHITE MOUNTAINS INSURANCE GROUP, LTD.

February 13, 2007

Date

/s/ J. Brian Palmer

Signature

Chief Accounting Officer

Name/Title

WHITE MOUNTAINS ADVISORS, LLC.

/s/ Mark J. Plourde

Signature

Chief Financial Officer,
Chief Compliance Officer and Treasurer

Name/Title