**Exhibit 31.1****CERTIFICATION UNDER SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002**I, Mark E. McMillan, certify that: 1. I have reviewed this quarterly report on Form 10-Q of Insignia Solutions plc;  2. Based on my knowledge, this quarterly report does not contain any untrue statementof a material fact or omit to state a material fact necessary to make the statementsmade, in light of the circumstances under which such statements were made, not misleadingwith respect to the period covered by this quarterly report;  3. Based on my knowledge, the financial statements, and other financial informationincluded in this quarterly report, fairly present in all material respects the financialcondition, results of operations and cash flows of the registrant as of, and for, theperiods presented in this quarterly report;  4. The registrant’s other certifying officers and I are responsible for establishing andmaintaining 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 ActRules 13a-15(f) and 15d-15(f)) for the registrant and have:     (a) Designed such disclosure controls and procedures, or caused such disclosurecontrols and procedures to be designed under our supervision, to ensure that materialinformation relating to the registrant, including its consolidated subsidiaries, is madeknown to us by others within those entities, particularly during the period in which thisreport is being prepared;     (b) Designed such internal control over financial reporting, or caused such internalcontrol over financial reporting to be designed under our supervision, to providereasonable assurance regarding the reliability of financial reporting and the preparationof financial statements for external purposes in accordance with generally acceptedaccounting principles;     (c) Evaluated the effectiveness of the registrant’s disclosure controls andprocedures and presented in this report our conclusions about the effectiveness of thedisclosure controls and procedures, as of the end of the period covered by this reportbased on such evaluation; and     (d) Disclosed in this report any change in the registrant’s internal control overfinancial reporting that occurred during the registrant’s most recent fiscal quarter (theregistrant’s fourth fiscal quarter in the case of an annual report) that has materiallyaffected, or is reasonably likely to materially affect, the registrant’s internal controlover financial reporting; and 5. The registrant’s other certifying officer and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to the registrant’sauditors and the audit committee of the registrant’s board of directors (or personsperforming the equivalent functions):     (a) All significant deficiencies and material weaknesses in the design or operationof internal control over financial reporting which are reasonably likely to adverselyaffect the registrant’s ability to record, process, summarize and report financialinformation; and     (b) Any fraud, whether or not material, that involves management or other employeeswho have a significant role in the registrant’s internal control over financial reporting.Dated:August 19, 2005              /s/ Mark E. McMillan   Mark E. McMillan   Chief Executive Officer