If the filing person has previously filed a statement on Schedule 13G to report the acquisition which 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. ¨

NOTE: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See § 13d-7(b) 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 the 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 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).

CUSIP No.: G0567U101

CUSIP No.: G0567U101

CUSIP No.: G0567U101

This Amendment No. 1 to Schedule 13D (this “Amendment No. 1”) is being filed by Heritage Assets SCSp (“Heritage Assets”), a Luxembourg company, M Management S.A., a Luxembourg company (“M Management”), and Manfredi Lefebvre d’Ovidio, an Italian citizen (collectively, the “Reporting Persons”), with respect to the ordinary shares, par value $0.0001 per share (the “Ordinary Shares”) of Arqit Quantum Inc., a Cayman Islands exempted limited liability company (the “Issuer”), to amend the Schedule 13D filed by the Reporting Persons on September 14, 2021 (the “Schedule 13D”).

No material changes.

No material changes.

Item 3 of the Schedule 13D is amended by adding the following as the penultimate paragraph thereof:

“On November 26, 2021, Heritage Assets sold 50,000 Ordinary Shares to each of Garth Ritchie and Cristina Levis at a price of $10.00 per Ordinary Share and transferred 48,105 Ordinary Shares to each of Garth Ritchie and Cristina Levis for no consideration, in each case, in a private placement. On November 29, 2021, Heritage Assets sold 400,000 Ordinary Shares to Carlo Calabria at a price of $10.00 per Ordinary Share and transferred 384,837 Ordinary Shares to Carlo Calabria for no consideration, in each case, in a private placement.”

Item 4 of the Schedule 13D is amended by adding the information in Item 3 of this Amendment No. 1.

Item 5 of the Schedule 13D is amended and restated in its entirety as follows:

“(a), (b) The responses of the Reporting Person with respect to Rows 7 through 13 of the respective cover pages of the individual Reporting Persons to this Schedule 13D are incorporated herein by reference.

The Reporting Persons’ aggregate percentage of beneficial ownership is approximately 6.7% of the outstanding Ordinary Shares. Calculations of the percentage of the shares of Ordinary Shares beneficially owned is based on 120,073,430 Ordinary Shares outstanding as of October 6, 2021.

(c) Except as set forth in this Schedule 13D, none of the Reporting Persons has engaged in any transaction with respect to the Ordinary Shares during the sixty days prior to the date of filing of this Schedule 13D.

(d) Not applicable.

(e) Not applicable.”

No material changes.

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.