Hi - I really think the best chance of finding more about Charles & Mary is to see the marriage register entries - as I said before these are normally less detailed than those in England or Wales of the same period, but I'd expect father's names (though not occupation) and ages of the couple (though could just be "full" - ie 21 or over). Particularly for Charles it would help in giving the period to look for his birth.
As I see wozzle has confirmed Mary's husband's birth it is possible someone has assumed they were both from the same area and hence the family story - like many it may be a mixture of truth and fancy.
I had another look on the BL's India Office index & Charles marriage is their earliest Haller entry - there's a marriage for a William Henry Haller in the 1871-1875 period - perhaps a relative of Charles? These indices are not complete, so there could be others or under variations of the name.
I Googled the name & found this link from 1875
http://www.london-gazette.co.uk/issues/24228/pages/3627/page.pdfHe's given as a "Telegraph signaller" and below him is Henry Maximillian Haller, a "clerk in the Times of India office" - a relative?
His name to me has echoes of a German name - I'm from the Manchester area & the founder of the local orchestra, Sir Charles Hallé, had anglicised his name from Carl (or Karl) Halle - which pronounced the German way would be nearer Haller - also August seems more of a "continental" name. Entering Charles August Haller on Familysearch produces several variants on Charles/Carl/Karl etc - mainly from continental Europe. That's all pure speculation and may well be a large red herring. I suspect it is a surname which derives from more than one source - there seem quite a lot of Haller births in Yorkshire, though none as Charles August that I found. I did find a Charles Augustus Harley, registered in the March quarter of 1850 in Lambeth.
This all may just be leading you up the garden path - best is to try & see the marriage entries - if you've a LDS Family History Centre near you can order the films at a cost & view them there; otherwise the BL have a research service - you got an exact date & place for one and a date range & LDS film for the other which should help keep their charges down. You could try asking for a look up on here (perhaps on the Common Room board with a link to this thread) - I don't get the impression many RootsChatters go to the British Library, but you could be lucky.
Good hunting!