I've had a quick look through the newspapers and there is a reference to the 1891 marriage but unfortunately it doesn't give any more info than has already been posted.
Bucks Herald 12 September 1891
Marriages
PRATT-SMITH - At All Saints' Church, Leighton Buzzard, on the 3rd inst., by Rev. T W Richards, M.A., vicar, George Pratt and Louisa Smith, both of Leighton Buzzard.
Also, if Louisa was a Smith then George and Louisa may have had more children than were listed in the 1901 census...
GRO BMD references:
1893 Q1 Birth - Florence Louisa Pratt (mmn: Smith); Leighton Buzzard; 03b; 378
1896 Q1 Birth - Lilian May Pratt (mmn: Smith); Leighton Buzzard; 03b; 369
1897 Q4 Birth - Alice Maud Pratt (mmn: Smith); Leighton Buzzard; 03b; 380
1898 Q4 Birth - Thomas Pratt (mmn: Smith); Leighton Buzzard; 03b; 377
1900 Q2 Birth - George Edward Pratt (mmn: Smith); Leighton Buzzard; 03b; 407
1893 Q1 Death - Florence Louisa Pratt; age 0 (b1893); Leighton Buzzard; 03b; 246
1900 Q3 Death - George Edward Pratt; age 2m?* (b1900)[1]; Leighton Buzzard; 03b; 221
* GRO index has age as 2 but FreeBMD has age as 0, so I presume GRO index age is days, weeks or months, which would tally with the death notice of 2 months.
Leighton Buzzard Observer and Linslade Gazette
24 January 1893
Deaths
PRATT - On the 21st inst., at Southcourt Road, Linslade, Florence, infant daughter of George Pratt, aged 12 days.
Leighton Buzzard Observer and Linslade Gazette
17 July 1900
Deaths
PRATT - On the 11th inst., at Vandyke Road, Leighton Buzzard, George Edward, son of George Pratt, aged 2 months.
EDIT: [1] Corrected estimated birth year for George Edward Pratt, based on presumed age at death of 2m.