See Castle Street East 1 to 15 &c in London Addresses dataset
No 4 Castle St East Land Tax 1781-1784 Sarah Williamson
(Possibly) / Charles Fellows of St Martins i t Fields bach = 1.12.1787 St Marylebone by lic Sarah Williamson (her mark) wid otp / Land Tax 1792 King St East (nr Baker St) St Marylebone Sarah Williamson / Sarah Williamson (adult) bur 4 or 6.1.1797 St Marylebone / SunFire 1807 sarah Williamson widow 36 Castle St Holborn / Sarah Paye Williamson bapt St Marylebone 5.9.1783 of Thomas & Elizabeth