Elizabeth,
Where was their first child born ?. This sometimes gives a clue to time and place of marriage.
What religion were they ?. (Up to July 1837, the only legal way to marry in England and Wales was in a Parish church , i.e. "Church of England"... some non-conformists e.g. Catholics, Methodists, Presbyterians, married over the border in Scotland to avoid marrying in the "wrong church" )
Berwick was sort of independent of both England and Scotland in that C19th era. Spittal, lying within the C o E Parish of Tweedmouth, lay legally in and under the juridiction of County Durham until 1844.
Michael Dixon
Newcastle