I don't believe Henry Moubray Michael was illegitimate. There is a marriage of John Hick Michael to Ann Martin in 1845:
Bombay Times and Journal of Commerce
Record details:
Marriages 1845 - marriages extracted from the domestic occurrences mentioned in the 1845 'Bombay Times and Journal of Commerce' which was the pre-cursor for the Times of India
Entry from Marriages 1845
Grooms Surname Michael
First names J H
Bride Martin
First names Ann
Place Calcutta
Year 1845
month July
day 9
Register Entry At Calcutta on the 9th July at St Thomas's Church Middleton Row by the Rev D Egan Mr J H Michael to Miss Ann Martin
Edition Year 1845
Edition Date 26 Jul
There is a birth of an unnamed son to John and Ann in 1852, which I believe is Henry:
Allens Indian Mail: Birth, marriages and death entries extracted from the domestic occurrences mentioned in Allens Indian Mail.
Bengal Births 1852
Entry from Bengal Births 1852
Surname Michael
Son/daughter son
Place Calcutta
Year 1852
Month February
Day 13
Exact Entry Michael, Mrs. J.H. s. at Calcutta, Feb.13.
Edition Year 1852
Edition Date 2 April
I got both of these from the FIBIS website a while ago. Also, I wonder if John Martin Michael and his daughter were 'American' or possibly this is a mistake for 'Armenian'? John Hick Michael's father was Hick or Haik Michael and his mother was Ripisma. They were Armenian.
"Armenians in India, from the earliest times to the present day: a work of original research. Pub by Asian Educational Services, 1937" by Mesrovb Jacob Seth
Chapter XXX111 The Armenian Church of Nazareth: the oldest place of Christian worship in Calcutta
p 439 "on a white tablet, fixed on the south wall of the nave:
18. "Sacred to the memory of John Michael, merchant of this city, the only child of Haik and Ripsima Michael, died at Calcutta on 4th February 1909, aged 75 years. Interred at the Tangra Cemetery.
this tablet was erected by the Church Committee in appreciation of the chrities endowed by him for the relief and education of the Armenian poor in Calcutta."
Mr John Haik Michael, the son of humble parents, rose through sheer merit, to be a leading merchant and land owner in Calcutta, during the last decades of the 19th century. He left large bequests for the poor Armenians of Calcutta* and for the education of poor Armenian boys and girls in the La Martiniere (for girls) and in the local Armenian College.
* Mr John Haik Michael left a bequest of Rs. 102, 600 to the Armenian Church of Calcutta for the benefit of the poor."
http://books.google.co.nz/books?id=BlreO8bmK30C&dq=%22john+haik+michael%22&source=gbs_navlinks_sI'd love to get any photos of Henry or his sons.