Who was Lord Tilbury?

Where is the borough of Garrett? does it still exist?

Some

  [Likeness of Tilbury shown as a monkey-like boyish Jester]
  
  "To the Independent Electors for the Borough of Garrett
  
  LADIES AND GENTLEMEN,
  
  I am not come forth to shew myself, as a candidate for this noble and ancient Borough of Garrett. Being Grand Uncle to Sir Jeffrey Dunstan, your late worthy Member, own Brother to his Dutchess [sic], Brother to Miss Nancy, and own Uncle to my Lord Thompson. I have every reason to believe that you have all heard that I was an enemy to the tax on gin, and am zealous to have a reform in Parliament, and to have a peace, it is ever so dishonourable. 
  
  Whatever Mr. Harper or Mr. Shineall have to say will avail nothing, for every one knowns the Green Grocer's principles, they are for himself. But I am for the community at large, and not to be baffled by any party; for it is the duty of every member to exert himself for the freedom of taxation, and to down with the price of gin, bread, and meat; that we may have a quartern [sic] loaf, a pot of porter, and a pound of cheese, for one shilling.
  
  SWINE-HOUSE SQUARE, JUNE 1796.  
  TILBURY.
  
  * * *
  
  AIR -- A-begging we will go
  
  Electors of fam'd Garrett, attend to freedom's call
  Lord Tilbury he is the man, I'm sure, to serve you all.
  
  CHORUS
  
  And for Tilbury let's vote, let's vote, let's vote
  So for Tilbury brave let us vote.
  
  Descended from the ancient house of Dunstan's noble name
  Own brother to Miss Nancy, that young lady of great fame
  
  His fortune it is very large, 'tis a numerous stock of wigs
  His taste is fine, he herds with swine and snores each night with the pigs
  
  He swears that gin it shall come down to what it was before
  And if you want a pot of stout, have liberty to score
  
  Pitt, Fox, and Sheridan, were taught in learned schools
  But Lord Tilbury can tip them both, to him they are but fools
  
  For bakers and cornfactors, he hates the knavish crew
  And the quartern loaf for sixpence, doth ever keep in view
  
  In Parliament he's for reform, if that it can be had
  And would patch up peace, at any rate, let the terms be good or bad
  
  For like his brother Patriots, he's got nothing for to lose
  And for England's fame or glory, to be careless, cannot chuse.
  
  So vote away without delay, Lord Tilbury on you waits
  And promises great things, like all other candidates
  
  [Satirical Anti-Tilbury song. From 1796. A new Patriot Song, in Favour of Lord Tilbury.]