Former Shell chief executive Ben van Beurden said he believes the company is "massively undervalued" in London.
On Tuesday he told the Financial Times at a commodities summit that US-listed companies benefited from a deeper pool of capital, higher valuations, and "more positive" attitudes from investors.
Van Beurden believes a discount between European and US-listed companies has "existed for a long time, and it will take a long time, maybe forever, to resolve."
"The share price today is at an all-time high, but it could be significantly higher from where it is today," he said.
Van Beurden's remarks follow similar comments by Wael Sawan, Shell's current chief executive, who expressed his reservations during an interview with Bloomberg on Monday.
Sawan told the news and data outlet the company is looking at "all options" for its listing amid concerns it is under-appreciated by investors.
"I have a location that clearly seems to be undervalued," he remarked, referring to London.
His comments sent alarm bells ringing that Shell, which is Britain's most-valuable listed company and worth around £183 billion, could become the latest blue chip business to flee the London market.
The London Stock Exchange, which has struggled to attract sizeable new listings, has suffered a string of high-profile transfers of primary listings.
Building materials firm CRH PLC moved its primary listing to New York in September. Plumbing and heating products supplier Ferguson PLC did the same in May 2022, months after miner BHP Group Ltd shifted its main listing to Sydney.
More recently, Paddy Power owner Flutter Entertainment PLC announced it was looking to move its primary listing to New York in May.
Shell shares were up 1.1% to £28.58 each in London on Wednesday morning.