Exhibit 99.1

 

YOUR VOTE IS IMPORTANT. PLEASE VOTE TODAY. Vote by Internet—QUICK EASY IMMEDIATE—24 Hours a Day, 7 Days a Week or by Mail GS ACQUISITION Your Internet vote authorizes the named proxies to vote your shares in the same manner as if you HOLDINGS CORP II marked, signed and returned your proxy card. Votes submitted electronically over the Internet must be received by 11:59 p.m., Eastern Time, on Xxx xx, 2021. INTERNET – www.cstproxyvote.com Use the Internet to vote your proxy. Have your proxy card available when you access the above website. Follow the prompts to vote your shares. Vote at the Meeting – If you plan to attend the virtual online annual meeting, you will need your 12 digit control number to vote electronically at the annual https://www meeting. To attend: .cstproxy .com/[X]/sm2021 MAIL – Mark, sign and date your proxy card and return it in the postage-paid envelope PLEASE DO NOT RETURN THE PROXY CARD provided. IF YOU ARE VOTING ELECTRONICALLY. FOLD HERE DO NOT SEPARATE INSERT IN ENVELOPE PROVIDED ï³ GS ACQUISITION HOLDINGS CORP II THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS The undersigned appoints Thomas R. Knott, as proxy, with the power to appoint his substitute, and authorizes him to represent and to vote, as designated on the reverse hereof, all of the shares of common stock of GS Acquisition Holdings Corp II held of record by the undersigned at the close of business on Xxxx xx, 2021 at the Special Meeting of Stockholders of GS Acquisition Holdings Corp II to be held virtually at: https://www.cstproxy.com/[X]/sm2021 on Xxxx xx, 2021, at XX:00 a.m. or at any adjournment or postponement thereof. THIS PROXY WHEN PROPERLY EXECUTED WILL BE VOTED AS INDICATED. IF NO CONTRARY INDICATION IS MADE, THE PROXY WILL BE VOTED IN FAVOR OF PROPOSALS 1 THROUGH 7, AND IN ACCORDANCE WITH THE JUDGMENT OF THE PERSONS NAMED AS PROXY HEREIN ON ANY OTHER MATTERS THAT MAY PROPERLY COME BEFORE THE SPECIAL MEETING. THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS. PLEASE MARK, SIGN, DATE AND RETURN THE PROXY CARD PROMPTLY. (Continued, and to be marked, dated and signed, on the other side)

Important Notice Regarding the Internet Availability of Proxy Materials for the Special Meeting of Stockholders The Proxy Statement and related materials are available at: https://www.cstproxy.com/xxxxxxxx/2021 PROXY CARD Please mark THE BOARD OF DIRECTORS RECOMMENDS A VOTE “FOR” EACH OF THE PROPOSALS. your votes like this X Proposal No. 1 — Approval of the Business FOR AGAINST ABSTAIN Proposal No. 4 — The Governance Proposals FOR AGAINST ABSTAIN Combination — To consider and vote upon a — To consider and vote upon a proposal to proposal to approve and adopt the Business approve, on a non-binding advisory basis, certain Combination Agreement, dated as of June 17, 2021 (as it may be governance provisions in the New Mirion Charter, presented separately further amended from time to time, the “Business Combination in accordance with the United States Securities and Exchange Agreement”), by and among the GS Acquisition Holdings Corp Commission requirements; II (the “Company”), Mirion Technologies (TopCo), Ltd., a Jersey Proposal No. 5 — The Director Election FOR AGAINST ABSTAIN private company limited by shares “Mirion”, for the limited purpose Proposal —set forth therein, CCP IX LP No. 1, CCP IX LP No. 2, CCP IX Co- To consider and vote upon a Investment LP and CCP IX Co-Investment No. 2 LP (collectively, the proposal to elect nine directors to serve, “Charterhouse Parties”), for the limited purpose set forth therein, each effective upon the closing of the Business Combination, on our Board of of the other persons set forth on Annex I thereto and, for the limited Directors until the 2022 annual meeting of stockholders, and until their purpose set forth therein, the other holders of A Ordinary Shares and B respective successors are duly elected and qualified, or until their earlier Ordinary Shares from time to time becoming a party thereto by executing resignation, removal or death; a Joinder Agreement, a copy of which is attached to the accompanying proxy statement/prospectus as Annex A; Proposal No. 6 — The Incentive Plan Proposal FOR AGAINST ABSTAIN — To consider and vote upon a proposal to Proposal No. 2 — The NYSE Proposal — FOR AGAINST ABSTAIN approve the Mirion Technologies, Inc. Omnibus To consider and vote upon a proposal to approve, Incentive Plan, including the authorization of the for purposes of complying with applicable listing initial share reserve under the Incentive Plan; rules of the New York Stock Exchange (the “NYSE”), (a) the issuance and of more than 20% of the Company’s outstanding Class A common FOR AGAINST ABSTAIN stock in connection with the Business Combination, including the PIPE Proposal No. 7 — The Adjournment Proposal Investment, and (b) the issuance of shares of the GSAH Class A — To consider and vote upon a proposal to common stock and the GSAH Class B common stock to a Related Party approve the adjournment of the Special Meeting (as defined in Section 312.03 of the NYSE’s Listed Company Manual) in to a later date or dates, if necessary, to permit further solicitation and connection with the Business Combination; vote of proxies in the event that there are insufficient votes for, or for any other reason in connection with, the approval of one or more of the other Proposal No. 3 — The Charter Proposal — FOR AGAINST ABSTAIN proposals at the Special Meeting. To consider and vote upon a proposal to adopt the Second Amended and Restated Certificate of Incorporation in the form attached to the accompanying proxy statement/ prospectus as Annex B (the “New Mirion Charter”), which, if approved, would take effect upon the closing of the Business Combination; CONTROL NUMBER Signature Signature, if held jointly Date , 2021 Note: Please sign exactly as name appears hereon. When shares are held by joint owners, both should sign. When signing as attorney, executor, administrator, trustee, guardian, or corporate officer, please give title as such.