Broadly speaking, the further north and west in the county you go, the more likely you are to encounter the Welsh language. A person studying a family in the east of Montgomeryshire may never need to understand a word of Welsh. On the other hand, a person with ancestors in the west of the county, especially nonconformist ancestors, is likely to come across the language at a fairly early stage.
Most written documents, even those produced by Welsh speakers, tend to be in English, which has for centuries been the language in Wales of officialdom. Even the registers of Welsh speaking chapels are likely to fall into this category.
The place where you are most likely to come across the Welsh language is in memorial inscriptions in church and chapel yards. In a country parish churchyard in the north and west of the county, between two thirds and three quarters of inscriptions are likely to be in Welsh. Sometimes the "official" details of name, age and date of death are in English, whilst the verse - the personal valedictory - is in Welsh. Below is a model gravestone with variations on the standard expressions used and an English translation.
Er Cof Am / Er Serchus Gof Am / Er Serchus Goffadwriaeth Am
In Memory Of / In Loving Memory Of / In Loving Remembrance Of
John Jones, Bronheulog, yn y Plwyf Hwn
John Jones, of Bronheulog in this Parish
Yr Hwn a Fu Farw / Yr Hwn a Ymadawodd ar Bywyd Hwn / Yr Hwn a Hunodd
Who Died / Who Departed this Life / Who Fell Asleep
Chwefror 12fed, 1900, Yn 70 Mlwydd Oed
February 12th, 1900, Aged 70 Years
Hefyd Am Mary
Also of Mary
Gwraig i'r Dywededig John Jones
Wife of the Said John Jones
Yr Hon a Fu Farw
Gorphenaf y 27ain 1910
July the 27th 1910
Yn 75 Mlwydd Oed
Aged 75 Years
Coffadwriaeth y Cyfiawn Sydd Fendigedig
The Memory of the Just is Blessed