(see 1799 William Lankshear marriage Elizabeth Parrott - Stoke Upon Trent)

Joseph's marriage found in Vicar General Marriage Licence Allegations (1694 - 1850)
from English Origins the original can be ordered at 10 pounds - but then also at FreeBMD 
16 Jun 1848 LANKSHEAR to Osborn This came up with search for Lankshear and  Thomas .Maybe there was a Thomas - father of Bride or Witness
also IGI Spouse: JANE OSBORN 
Marriage: 17 JUN 1848 All Souls, Saint Marylebone, London, England 

see also 1839 Joseph Lankshear marriage Hannah Higham in Kensington possible 1st marriage

Jane Osborn is presumed in view of 1871 census Jane & Louise LANKSHEAR Governess at Deptford
which shows Jane  living as head but married not widow - aged 56 hence born c1814

But living with her is Edgar OSBORN, brother which leads to this marriage 

also Jane Lankshear Deaths Dec 1892  79  W Ham  4a 90 

FreeBMD Marriages Jun 1848 Marylebone 1188 

HOLDEN  Honore  JEYNES Edmund  Lankshear Joseph  Minet Charlotte Ann  Murray Louisa Ruperta  Osborn Jane 

1807 JOSEPH LANKSHEAR son William and Elizabeth  

1851 Joseph and Jane (Osborn) Lankshear census with Emily and Louisa and 1850 Emily Lankshear in St James daughter of Joseph and  Jane

Grace Lankshear - International Genealogical Index  (added 8/2004)
Gender: Female Christening: 28 MAY 1852 St James, Westminster, London, England
Birth: 04 MAY 1852 Father: Joseph Lankshear Mother: Jane Lankshear 
FreeBMD Births Jun 1852 LANKSHEAR Grace Kensington 1a 70 

but in 1861 census JOSEPH LANKSHEAR the surgeon is living alone and also 1845 Joseph Lankshear declared BANKRUPT -

1845 Times and 1846 Joseph Lankshear bankrupt

 It seems that he married Jane in 1848 and they separated.