Mary and Mally: were they used interchangeably in Yorkshire in the late 18th century?

Question

In my previous question on Finding the Fatherless Feathers, I made reference to a Mally Thomas with whom the Feather siblings seemed to be lodging in 1841, in Heptonstall, Yorkshire, England.

In 1851, Sarah Feather was still lodging with a Thomas family, this time a Richard and Mary Thomas, in Manningham, but the implied birth dates of Mary and Mally are similar, and both Richard and Mary were born in Heptonstall. If so, it is probably the Mary Feather and Richard Thomas who married in 1818 in Halifax parish, which includes Heptonstall.

I have found a burial record for a Mally Thomas in 1860 in Manningham, which would be consistent with Richard Thomas turning up as a widower in the 1861 Census (still living with Sarah, now recorded as his “daughter” rather than as a “lodger” as in 1851). That there was a family connection seems consistent with the fact that in 1871, Sarah was still living at the same address without Richard, as they both were in 1861. That would be strange if she was just a lodger.

If Mally was often recorded as Mary, and vice versa, then it seems reasonable to suppose that Mally Thomas in the 1841 Census was the Mally Fether mentioned in the birth record Adrian found and posted as an answer to my earlier question. The Feather siblings living with Mally Thomas in 1841 were therefore living with their since-married mother, and it therefore seems that most of the family moved to Manningham before 1849 (when Penelope died, in Manningham). It would also seem reasonable to hypothesise that Mary Thomas of 1851 was the Mally Thomas of 1841 and of the death record in 1860.

Even if Mally and Mary are not the same person, it seems reasonable to suppose that Sarah (and John) Feather were lodging with some sort of relatives in Manningham, given that Mary's maiden name probably was Feather.

So my question is, can I treat Mally = Mary in records for late 18th century / early 19th century Yorkshire, if I have reason to hypothesise that the records are referring to the same person?

Answer 1

This does not seem very authoritative but Answers.com says:

The name Mally is a medieval diminutive form of the name Mary, and was a pet, or affectionate form of the name Mary. 16th century records in Scotland showed it in common usage there. Some say its origin is English, but there is also reason to find its origin Scot.

It suggests your theory is at least reasonable.

Further searching finds more authoritative evidence that Mally is a "pet name" for Mary. Although the web-site linked ("WhatsInAName") is primarily aimed at names in Scotland, their source is "The Oxford Names Companion" (OUP) and indicates that the usage is in both Scots and English. Mally was apparently the original pet-name for Mary and eventually evolved into the perhaps more familiar Molly.

Completing the chain of references, The Oxford Names Companion (2002) from OUP has:

• An entry for Mally as a surname (anglicised form of Gaelic O Maille)
• No entry for Mally as a forename
• An entry for Mary as a forename showing Mailli as a Scottish Gaelic cognate and Molly as an English pet form
• An entry for Molly stating it is English and Irish, and a "long-established pet form of Mary, representing an altered version of the earlier pet form Mally."