Exhibit 15.1

Consent of Independent Registered Public Accounting Firm

We hereby consent to the incorporation by reference in the following Arqit Quantum Inc. registration statements:

(1)registration statement on Form S-8 (File No. 333-262215);

(2)registration statement on Form S-8 (File No. 333-275960);

(3)registration statement on Form S-8 (File No. 333-284706);

(4)registration statement on Form F-3 (File No. 333-268786);

(5)registration statement on Form F-3 (File No. 333-259982);

(6)registration statement on Form F-3 (File No. 333-284343); and

(7)registration statement on Form F-3 (File No. 333-289939).

of our report dated December 9, 2025, relating to the financial statements which appear in the Arqit Quantum Inc. Annual Report on Form 20-F for the year ended September 30, 2025. We also consent to the reference to us under the heading “Experts” in such Registration Statements.

__________________

PKF Littlejohn LLP

London, United Kingdom

December 9, 2025