Is the name 'Irans' or 'Irons'?
Probably no connection with your Frances and John, but I thought the following was interesting, given the above suggestion…
1881 Glasgow Anderston census - possibly your Beggs couple?
Ann Duffy, age 33, born Ireland and Hugh Duffy, age 6. In the same household, recorded as other relatives:
“Francies Biggs”, born c1858, Perth
John Biggs, age 29
Annie Biggs, age 2
1861 Glasgow census - possibly the same Ann?
Ann Duffy, age 18, born c1843, Ireland
(Father) John Duffy, age 48
(Mother)
“Agne Iran Duffy”, age 40
Jennes, age 21
John, age 15
Elizabeth, age 13
After a quick search, I could not find John and Agne Iran Duffy in 1871.