Looking at what we definitely know about RC's parents and early life------

I've seen a draft copy of Richard Costain's entry in New Manx Worthies, and the impression is given that he came from a farming family ( I think that the info came from a grandson of RC, Sir Albert Costain MP, in his unfinished work "Reflections" which I haven't seen.) However, I believe that both the 1841 and 1851 censuses show RC b1839 as being the son of a fisherman, and this is confirmed by his marriage entry in the Rushen parish register, a transcription of which was supplied by my very kind, diligent cousin who saw the entry at her local FHC.

8 Mar 1866 Richard Costain / Margaret Kneen both full age bachelor/spinster respectively. He. A "Joiner & Builder" of Southport, Lancashire she of "Cross e Caley". His father Richard Costain -Mariner. Her father, Richard Kneen - Farmer
Married in the Established church by licence, witnessed by William Kneen and Thomas Kneen. Richard Costain and Margaret Kneen both signed. Marsden Gibson, Curate.

I can't find his baptism entry in the IGI. His age at death (63) in Sep Q 1902 gives a birth year of 1839. There is no RC listed with a father's name of Richard in the relevant time frame. The RC I've found in the 41 (Croit e Caley) and 51(Colby) censuses has parents named Richard and Elizabeth. In 1851 there's a Henry Redhead age 31, tailor, living in the same household.

1841 Croit e Caley
Richard Costain age 30 Fisherman
Elizabeth Costain age 25
Richard Costain age 2

1851 Colby
Richard Costain Head age 40 Fisherman born Arbory
Elizabeth Costain Wife age 34 born Arbory
Richard Costain son age 12 Scholar born Arbory
Henry Redhead Lodger age 31 Tailor born Arbory

The IGI has a Henry Redhead bap 19 March 1820 Arb, parents Robert Redhead and Jane Cubbon. These same parents have a daughter Elizabeth Redhead bap 3rd June 1816 Arb.

This is as near as I can get to proving that the parents of RC b1839 were Richard Costain and Elizabeth Redhead.

Coming from a different direction, this is an extract from an old FHS journal:

Isle of Man Family History Society Journal Volume vii no 4 Nov 1985
"Ritchey Betsy" Costain

Wm. Cubbon, Manx Museum., Director & Librarian (1865-1955)

"At the end of July 1951, while Harry and I were motoring along the Embankment in London, I saw, planted on a large wooden structure in the river, the name of Richard Costain & Sons. They were, Harry (Cubbon) said, the builders of a new bridge across the river for the Festival of Britain. The story of ‘Ritchey Betsy’ came into my mind, and of his struggles in the 1870s and 1880s in England.

'Ritchey Betsey' was so called because his mother was a Betsy Costain (Betsy Redhead); I don’t know the name of his father, but she was
one of the Costains, Ballachrink, and she gave her name to her son, Richard. ( Comment by JC, 1st Feb 2009----this might give the impression that Richard Costain was illegitimate, which definitely isn't true. His parents, Richard Costain and Elizabeth Redhead, married on 10th Jan 1839, Arbory )

When Richard had learned the trade of a joiner in Colby village, he undertook bigger jobs than most young fellows, and was looked upon as one of the best craftsmen in the parish of Arbory.

Richard emigrated to England and settled near Blundellsands, Liverpool.

He soon saved a bit of money, like those of the Ballachrink family did, and was lucky in his speculations. He built several houses of the working class type, sold them and built others. He would buy a tract of land and build terrace after terrace, and soon was looked upon as a most successful and capable builder. He was wise enough to get a few of his old chums in Kirk Arbory to work as masons and joiners for him. A few of them I knew, such as Joe Karran of Croit-e-Caley, but he got some of his own blood as well. I think he married a Kneen of Croit-e-Caley, and one of the family went out and helped him very materially, financially and otherwise. I remember as a boy of about six or eight seeing coming to our house a son of Ritchie Betsy. He was visiting the Kneens a few yards from our home. The boy was about the same age as myself, but he was precocious. There were about five or six of us youngsters in our kitchen, and this young Costain took to bossing the lot. He said: "Now we’ll have service, for this is a chapel". He played the harmonium on a comb, and after a hymn he took a prayer, and we all joined in properly at the end, doing ‘Our’ Father’ very well he said. He then read a lesson; it was a parable. Then he preached the sermon. It lasted about five or six minutes and we all thought it most inspiring. I forgot to say that on all occasions when he spoke, he got on to the little round kitchen table, and we all sat around, some on chairs and some on a form, and the fire was out when mother came in. It may be that this precocious youth became the Rev. A.J. Costain who was for a large number of years the Principal of Rydal Mount School, Colwyn, who I know was the son of ‘Ritchie Betsy’. He wrote in 1930 a charming account of T.E. Brown, in the Memorial volume published in that year."

Notes:
1. The firm of Richard Costain & Sons is now celebrated in Mann.
St. Ninians Church, a noble edifice, was erected by the firm, and stands in a prominent part of Douglas, a fine memorial to the late H.B. Hoble, — and the Costains too. The firm in 1951 built the Cubbon Memorial Wing at Noble’s Hospital, and is at present building the new Nurses’ Home.
2. As the Rev. A.J. Costain was born in 1881, the small boy must have been one of his elder brothers, either Arthur, Henry or Percy.
R. Kissack

I have a very nice photo of RC b1839 which was taken in 1871. It's from a collection of several of RC's wife's Kneen family, on the occasion of the marriage of Mgt Kneen's sister, Elizabeth b 1848. She married Thomas Crye in Liverpool. So RC is aged 31 in this photo. The matching one of Margaret shows her with her 2 eldest children, Richard Arthur Costain b 1867 and Henry Kneen Costain b 1869.

JC