See Poland Street 1 to 9 & 49 to 62 in London Addresses dataset.
Sun Fire 1777 George Ritso (QV*) at Mr Harris's coal merchant 2 Poland St / SunFire 1780 Thomas Harris gent 1 Poland St / 1780 Thomas Harris Poland St voted Rodney & Lincoln / Ratebooks Thomas Harris 1781-2 1 Poland St / Ratebooks Thomas Harris 1784-6 3 Poland St
Even assuming that the Harris at 1, 2 & 3 Poland St are one and the same, the name is too common to make a further identification. Saw will PCC 1794 of Thomas Harris coal merchant at Henley, no apparent links with London. Will PCC 1792 of Thomas Harris victualler of Silver St mentioned wife Sarah