Question: Cressida Dick, currently the Commissioner of Police of the Metropolis, operates as the head of what?

Context paragraphs:
Joseph Simpson: Sir Joseph Simpson, KBE, KPFSM (26 June 1909 – 20 March 1968), commonly known as Joe Simpson to his men, was Commissioner of Police of the Metropolis, the head of the London Metropolitan Police, from 1958 to 1968.  He was the first Commissioner who began his police career as an ordinary constable.

Cressida Dick: Cressida Rose Dick, {'1': ", '2': ", '3': ", '4': "} (born 16 October 1960) is a British senior police officer, currently the Commissioner of the Metropolitan Police in London.  She is the first woman to take charge of the service, being selected for the role in February 2017 and taking office on 10 April 2017.

Deputy assistant commissioner: Deputy assistant commissioner (DAC), formally Deputy Assistant Commissioner of Police of the Metropolis, is a rank in London's Metropolitan Police Service between assistant commissioner and commander.  It is equivalent to deputy chief constable in other British police forces and wears the same insignia: a pip above crossed tipstaves within a wreath.

John Stevens, Baron Stevens of Kirkwhelpington: John Arthur Stevens, Baron Stevens of Kirkwhelpington, (born 21 October 1942) was Commissioner of Police of the Metropolis (head of the Metropolitan Police Service) from 2000 until 2005.  From 1991 to 1996, he was Chief Constable of Northumbria Police before being appointed one of HM Inspectors of Constabulary in September 1996.  He was then appointed Deputy Commissioner of the Met in 1998 until his promotion to Commissioner in 2000.  He was a writer for the "News of the World", for £7,000 an article, until his resignation as the hacking scandal progressed.

Richard Mayne: Sir Richard Mayne KCB (27 November 1796 – 26 December 1868) was a barrister and the joint first Commissioner of Police of the Metropolis, the head of the London Metropolitan Police (1829–1868).  With an incumbency of 39 years, he was also the longest-serving Commissioner in the force's history, as well as the youngest on his appointment.

James Monro: James Monro CB (1838 – 28 January 1920) was a lawyer who became the first Assistant Commissioner (Crime) of the London Metropolitan Police and also served as Commissioner of Police of the Metropolis from 1888 to 1890.

Deputy Commissioner of Police of the Metropolis: The Deputy Commissioner of Police of the Metropolis, commonly referred to simply as the Deputy Commissioner, is the second-in-command of London's Metropolitan Police Service.  The rank is senior to Assistant Commissioner, but junior by one rank to Commissioner.  The Deputy Commissioner's salary from 1 September 2010 is £214,722, making them the second highest paid British police officer.

Bhim Sain Bassi: Bhim Sain Bassi or more commonly B.S. Bassi (born 20 February 1956) is an Indian civil servant and law enforcement officer and is currently a Member of the Union Public Service Commission since 31 May 2016.  He served as the Commissioner of Police, Delhi from August 2013 to February 2016.  He previously served as the Special Commissioner of Police (Administration) of Delhi Police (2012–13), Special Commissioner of Police (Traffic) of Delhi Police (2011-2012), Director General of Police of Goa Police (2009-2011) and Inspector General of Police of Chandigarh Police (2000-2002).

Commissioner of Police of the Metropolis: The Commissioner of Police of the Metropolis is the head of London's Metropolitan Police Service.  The post is currently held by Cressida Dick, who assumed office on 10 April 2017.

List of Commissioners of New South Wales Police: The Commissioner of the New South Wales Police Force (Known from 1851 to 1926 as the Inspector-General of the New South Wales Police Force) is the head of New South Wales's Police Force.  The post is currently held by Mick Fuller, who replaced Andrew Scipione on 31 March 2017.  The rank is usually referred to as the New South Wales Police Commissioner or simply just "Commissioner".  The New South Wales Police Force has had 22 Commissioners since 1851.

Supporting paragraphs: Commissioner of Police of the Metropolis Cressida Dick
Answer: London's Metropolitan Police Service