The deputy prime minister's political aspirations aren't the only thing about him that is endangered.
His surname is one of tens of thousands that have disappeared over the last 100 years, according to new research.
Surnames such as Clegg, William, Cohen, Kershaw, Sutcliffe, Butterworth and Greenwood are in danger of dying out, the study found.
Family history website Ancestry.co.uk compared surnames from the 1901 censuses with those from modern records and found that many had disappeared, including Chips, Hatman, Rummage, Nithercott, Raynott, Temples, Southwark and Woodbead.
William was the 374th most common surname in 1901, but has fallen to 12,500th today, said Ancestry.
Many which have vanished were anglicised by their owners, including immigrants who changed their name to avoid complications with the spelling of their foreign names.
The First World War also played a part in wiping out some names as specific battalions suffered mass casualties during the conflict, with towns or villages losing a generation of young men, said the report.
Miriam Silverman of Ancestry.co.uk said: "As a nation we've become more interested in where our names come from and what they mean. To many, a name is more than just a label - surnames are often steeped in history and identity, so nowadays a rare surname is something to be treasured rather than changed."