Question:
Which position did William Plumer hold in Dec, 1801?

Context:
 William Plumer holds the position of Member of the 16th Parliament of Great Britain from Mar, 1784 to Jun, 1790. 
 William Plumer holds the position of Member of the 1st Parliament of the United Kingdom from Jan, 1801 to Jun, 1802. 
 William Plumer holds the position of Member of the 3rd Parliament of the United Kingdom from Oct, 1806 to Apr, 1807. 
 William Plumer holds the position of Member of the 13th Parliament of Great Britain from Mar, 1768 to Sep, 1774. 
 William Plumer holds the position of Member of the 7th Parliament of the United Kingdom from Mar, 1820 to Jan, 1822. 
 William Plumer holds the position of Member of the 15th Parliament of Great Britain from Sep, 1780 to Mar, 1784. 
 William Plumer holds the position of Member of the 2nd Parliament of the United Kingdom from Jul, 1802 to Oct, 1806. 
 William Plumer holds the position of Member of the 12th Parliament of Great Britain from Feb, 1763 to Mar, 1768. 
 William Plumer holds the position of Member of the 14th Parliament of Great Britain from Oct, 1774 to Sep, 1780. 
 William Plumer holds the position of Member of the 18th Parliament of Great Britain from May, 1796 to Jan, 1801. 
 William Plumer holds the position of Member of the 17th Parliament of Great Britain from Jun, 1790 to May, 1796. 
 William Plumer holds the position of Member of the 5th Parliament of the United Kingdom from Oct, 1812 to Jun, 1818. 
 William Plumer holds the position of Member of the 6th Parliament of the United Kingdom from Jun, 1818 to Feb, 1820.

Answer:
Member of the 1st Parliament of the United Kingdom