EXHIBIT 12.1



CERTIFICATION PURSUANT TO RULE 13a-14(a)



OF THE SECURITIES EXCHANGE ACT OF 1934



I, Jonathan Lewis, certify
that:



| | 1. | I have received this
annual report on Form 20-F of Amec Foster Wheeler plc;                                                                                                                                                                                                                               
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| | 2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or
omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this report;



| | 3. | Based on my knowledge, the financial statements, and other financial information included in this
report, fairly present in all material respects the financial condition, results of operations and cash flows of the company as
of, and for, the periods presented in this report;
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| | 4. | The company’s other certifying officer and I are responsible for establishing and maintaining
disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial
reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the company and have:
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a) Designed such disclosure
controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that
material information relating to the company, including its consolidated subsidiaries, is made known to us by others within those
entities, particularly during the period in which this report is being prepared;



b) Designed such internal control
over financial reporting or caused such internal control over financial reporting to be designed under our supervision, to provide
reasonable assurance regarding reliability of financial reporting and the preparation of financial statements for external purposes
in accordance with generally accepted accounting principles;



c) Evaluated the effectiveness
of the company’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness
of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and



d) Disclosed in this report
any change in the company’s internal control over financial reporting that occurred during the period covered by the annual
report that has materially affected, or is reasonably likely to materially affect, the company’s internal control over financial
reporting; and



| | 5. | The company’s other certifying officer and I have disclosed, based on our most recent evaluation
of internal control over financial reporting, to the company’s auditors and the audit committee of the company’s board
of directors (or persons performing the equivalent functions):
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a) All significant deficiencies
and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to
adversely affect the company’s ability to record, process, summarize and report financial information; and



b) Any fraud, whether or not
material, that involves management or other employees who have a significant role in the company’s internal control over
financial reporting.



|Date: 28 April 2017 | /s/JONATHAN LEWIS      
|------------------- | -----------------------
|                    | Jonathan Lewis         
|                    | Chief Executive Officer