Explanation

Sardar Hukam Singh, Jagjivan Ram, Inderjit Gupta, Somnath Chatterjee and Seth Govind Das all served as pro-tem Speakers of the Lok Sabha — the senior member designated to swear in newly elected members and preside over the House until a Speaker is elected. Parliamentary records place Inderjit Gupta as pro-tem Speaker of the 10th Lok Sabha in 1991, and Somnath Chatterjee served as pro-tem Speaker of the 14th Lok Sabha in 2004 before his election as Speaker. They did not share the distinction of having been regular Speakers or Deputy Speakers in this common capacity. Hence what they have in common is having been pro-tem Speakers.