The following information is taken from deeds of the property in the hands of the owners in 2008.

Plan from deed of 24 June 1912

 

The plan to the right is from a deed of 24 June 1912.  Outlined in pink is the area which is the subject of much of the analysis below. 

At this date Sarah Amelia Crick and James Richard Crick were living in Ferryhill, Durham where they appear to have followed James Crick, Sarah Amelia's brother.  James Richard Crick was a son of Charles Crick, brother of Amelia and James, and was brought up by them.  Neither James nor Sarah Amelia seem to have married.  They went to Durham to farm.  James died in 1909 and James Richard inherited his half of the interest in the houses in Hanslope.

Nos. 10 and 12 High Street are to the South-West of the plot (bottom right in the plan).

Below are sections from earlier maps showing the development of the site.
1779
From map of 1779
The buildings which form the core of nos.10 and 12 High Street are shown on plot 661 owned by William Kitelee.  He bought in 1763.  In 1768 he had sold the plot 662 to Abraham Phillips.

William Kitelee bought from Stephen and Jane Holloway.  Earlier owners include Thomas and Sarah Webb, Thomas and Elizabeth Saul and Christopher Troughton, father of Elizabeth Saul.
1818
from map of 1818
 

Charles Crick purchased the plot 449 which included 10 and 12 High Street in 1811.  At this time plots 454 and 449 were owned by Elizabeth Barratt.  Plot 450 was owned by Aaron Warwick.

Descendents of Charles Crick sold 10 and 12 High Street in 1934, but another Crick purchased in 1954 and did not sell until after 1990.

  
1881
From first Ordnance Survey map of 1881
Plots 456, 7, and 8 were owned by Jane Crick, widow, who as Jane Hutchings had married James, son of Charles Crick.  Jane was brought up in Hanslope; her father was a maltster and probably owned 32 High Street, The Elms.

The earliest deed which has survived is dated May 1809.  However, it contains a schedule summarising earlier documents which were then in the possession of Mary Barratt who owned what is now 14 High Street.  It appears that before 1768, the land on which 12 and 14 High Street stand was in the same ownership, and the deeds had passed to the owners of 14 High Street when it was sold.  The list below is ordered by date, and starts with information extracted from the schedule to the 1809 document.

Period Probable owner Probable tenant Comments
sometime
before 1721		 Christopher Troughton   This is likely to be Christopher Troughton buried in 1658 who had a daughter Elizabeth, christened in 1654
to 1721 Thomas and Elizabeth Saul, ne Troughton   Elizabeth was the second wife of Thomas Saul, late of Hanslop.  She was daughter and heir to Christopher Troughton
1721 to 1745 Thomas Webb of Shuthanger, Northants, and Sarah his wife   Three persons were transferors of property:
* Christopher Saul of Coutenhall, Northants, gentleman
* Hercules Saul of London, jeweler, son and heir of Thomas
* Thomas Saul of London, cooper, son and heir of Thomas by Elizabeth
Robert Webb and Richard Mawby of Shuthanger were also parties to the transaction
1745 to 1763 Stephen Holloway of Hanslope, joiner  

Transfer was from Thomas Webb, labourer and son and heir of Thomas Webb gentleman. William Windmill of Hanslope was also a party to the transaction. 
A later mortgage was in name of Stephen Holloway and Jane, his wife; mortgagor was Joseph Churchill of Castlethorpe, yeoman; later transferred to Thomas Osborne of Stoke Goldington, shopkeeper
1763 to 1784 William Kitelee of Hanslope, lace merchant   There was also an assignment of mortgage to William Kitelee, also involving Joseph Kitelee of Castlethorpe, yeoman as trustee for William Kitelee
1784 to 1809 John Kitelee yeoman and Charlotte Kitelee his wife Occupied by Kitelees for a period; later William Wallinger and ffreeman Gregory
then
 John Kitelee was a son of William Kitelee, the latter described as "the elder".  The lease and release for the purchase by John Kitelee are dated 1st and 2nd of October 1784.  John and Charlotte were married on 22nd January of the same year.
1809 to 1811 Edmund Goodwin of Newport Pagnell surgeon

Charles Goodwin "in occupation" at time of purchase

James Whitbread was a tenant for period

1809 transferor was John Kitelee who had "survived Charlotte his late wife".  The property transferred include "two cottages or tenements ... (being formerly part of one messuage heretofore divided into three tenements)"
The transfer also included orchards and pastures as far as Maltmill Lane "formerly in occupation of John Goff and Thomas Panter ... and late in the occupation of William Thompkins" bounded on West by Land of William Allen and Charles Bishop and on South by close of Mary Barratt.  On 25 June 1811, there was some exchange of land with Mary Barratt.
1811 to 1846 Charles Crick of Hanslope, baker by his death Charles Crick was living at Woad Farm; not clear if 12 High Street let Charles Crick purchased on 1, 2 November.  Thomas Hindes was a party to the transaction "in trust for Charles Crick".
1846 to 1872 James Crick of Hanslope Indicated that, at least for a time, James occupied the premises James, son of Charles Crick was main beneficiary of the latter's will
The deeds contain no evidence of a will of James Crick, but according to a headstone in the Churchyard, James died on 8th February 1872
In the 1871 census the family is recorded as living in the High Street, so probably in No.12.
1872 to 1876 Jane Crick of Hanslope widow   Jane was the widow of James Crick. 
1876 to 1881 Charles Wilson Crick of Hanslope, farmer   Jane sold to her son for £600.
In the 1881 Census Charles and his family were living in the High Street, probably in No.12.  Jane and her children were tenants at Woad farm.
1881 to 1889 Jane Crick of Hanslope widow

by 1889:

house yard and garden occupied by Dr Ryan "or his undertenants"

shop and premises occupied by Mrssrs Clark and Webb

 Jane repurchased from Charles for £1,150.  The most significant difference in the description of the premises is the addition of "all that building erected and built upon part of the said Close or Pightle .. and fronting a Street or Road called Malt Mill Lane now in the tenure of Charles Groocock". 
Jane raised a mortgage of £400 to complete the transaction.  The mortgage deed contains a reference to "the shop stables chaishouse ..." as well as the buildings on Maltmill Lane.
Jane Crick's will contains a reference to "premises occupied by the Salvation Army".
1889 to 1910 James Crick and Sarah Amelia Crick from 25 March 1892 No. 10 let to Edwin Eakins James and Sarah Amelia were brother and sister who inherited under the will of their mother Jane.  Neither seems to have married, but as requested in their mother's will they brought up the two children of their deceased elder brother Charles Wilson Crick.
Agreement with Edwin Eakins witnessed by Joseph Crick.
1910 to 1915 James Richard Crick and Sarah Amelia Crick   James Crick Crick died 20 January 1910, and his half-share of the properties was inherited under letters of administration by his nephew James Richard Crick, son of Charles Wilson Crick.  At the time they were in Ferryhill, Durham where James was farming. 
1915 to 1934 Sarah Amelia Crick and Ada Crick

in 1926:

Dr Rutherford is tenant of a building

Edward Eakins is tenant of messuage or tenement shop yard land and premises

James Richard Crick died on 31 August 1915 at Ferryhill.  In his will he is identified as a Brass Finisher.  He left his real estate in trust for the benefit of his wife Ada for her life or until she remarried, and then to his children.  The trustees were Sarah Amelia, his aunt and Ada.
A description of the entire property in 1926 includes reference to "a building (part of which was sometime since converted to a Cottage) erected by Charles Wilson Crick ... fronting ... Maltmill Lane formerly in occupation of Charles Groocock afterwards of the Salvation Army and now in the occupation of Frederick Wesley." 
A memorandum on another document indicates that in 1926 part of the property fronting Maltmill Lane including "the wheelwrights workshops wash-house pigstyes yard and garden" was conveyed to William Dickins of Hanslope, builder.
A further addition to this document records that the mortgage taken out in 1881 by Jane Crick was repaid in 1926 when Ada Crick is recorded as living in St Albans, and Sarah Amelia Crick in Hanslope.
1934 to 1953 Robert William Dickins of Hanslope, builder   Sarah Amelia Crick and Ada Crick sold on 30 July 1934  By this time, Ada Crick was in Hoddesdon, Herts; and Sarah Amelia Crick in Moulton, Northants.
1953 to after 1990 Walter Herbert Crick and Albert Frederick Crick   At time of purchase letters were addressed to both Cricks at 22 Castlethorpe Road.
A letter of 1971 is addresses to A F S Crick only at 12 High Street.  There is no evidence for Walter Herbert Crick's involvement after 1959.
Source of above information: Deeds held by owner of property in 2008

Footnote: It is notable that most of the male descendents of Charles and Sarah Crick died young: son James at age 48; grandsons: Charles Wilson under 40, James 44, Joseph Hutchings 38; and great-grandson James Richard at 36.