back again.....
If I had looked a bit further it seems
Henry Baines born 1884 died.
Deaths Mar 1884
BAINES Henry 0 Leighton Buzzard 3b 239
Births Dec 1877
Guess Annie Leighton Buzzard 3b 417
Births Jun 1879
Baines Martha Leighton B. 3b 418
Mary appears to have had 2 children (Henry and Ann) prior to marrying Thomas Baine. Could she have been married before to ? Guess.

It may be worth getting Henrys birth cert.
1891 Census Leighton Buzzard
Thomas Baine 44 Leighton Buzzard Gen. Lab.
Mary Baine 40 Heath & Reach, Bedfordshire
Harry Baine 17 Leighton Buzzard Gen.Lab
Matha Bains 11 Leighton Buzzard
Marriages Jun 1897
Cox Angelina Leighton B. 3b 884
Guess Harry Leighton B. 3b 884
From the war record of Harry Guess he married Angelina Cox and has 4 children listed on the record. I assume you have this info.
Kind Regards
mariac