On his father's death Cottrell became Master of the Ceremonies. He was also vice-president of the Society of Antiquaries. In 1734 he was described by Hearne as "a scholar and an antiquary, and well skill'd in matters of proceeding and ceremony".
Cottrell died on 13 October 1758.
Cottrell married Bridget Sherborne (1696–1731)—only daughter and heir of Davenant and Mary Sherborne of Pembridge, Herefordshire—on 14 April 1716. They had two sons and five daughters who reached maturity:
- Charles (1720–1779), who followed in the family footsteps and became master of the ceremonies.
- Robert (died 1744), became a marine, perished at sea, and predeceased his father.
- Mary (died 1753), predeceased her father.
- Bridget (1719–1801), their second daughter became a maid of honour to Princess Anne.
Sir Clement's son, who died in 1779, and grandson, who died in 1808, each became Master of the Ceremonies. In 1900 the family was represented by C. Cottrell Dormer, and in his library contained a valuable collection of letters and papers relating to Sir Charles Cotterell, Sir Charles Lodowick, and Sir Clement Cotterell.
- Before 1741 Cottrell-Dormer was known as Clement Cottrell or Clement Cotterell 
- Clayton 2008.
- Lee 1887, p. 291.
- Lee 1887, p. 291 cites Hearne (28 June 1734) Reliquiæ Hearn. iii. 144.
- Deed Poll Office: Private Act of Parliament 1741 (15 Geo. 2). c. 7
- Lee 1887, p. 291 cites Hist. MSS. Comm. 2nd Rep. 82–3.
- Clayton, Roderick (January 2008) . "Cottrell , Sir Clement (1686–1758)". Oxford Dictionary of National Biography (online ed.). Oxford University Press. doi:10.1093/ref:odnb/6399.CS1 maint: ref=harv (link)<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles> (Subscription or UK public library membership required.)