indispensable

Mycroft draws four hundred and fifty pounds a year, remains a subordinate, has no ambitions of any kind, will receive neither honour nor title, but remains the most indispensable man in the country.”

“Then,” said he, “you are ready to pay the official visits, which are absolutely indispensable?”

“They were indispensable.”

“Ah, perbacco, indispensable, were they?”