How Tricky to Pin Down Hillingdon CLARK(E)s?

[supermoussi]

There is the following marriage listed in Hillingdon on a*y

 11 Oct 1817 James CLARK & Sarah WELSH (signed WELCH) both of this parish

and then also

 1 Aug 1819 Henry CLARK & Sarah OLNEY both of this parish

Having just attempted to see if they had any children baptised in Hillingdon, etc on a*y, familysearch & the Hugh Wallis site I can't seem to do this. Either I am being a dolt or aren't the Hillingdon baptisms and burials online yet?

I am primarily trying to prove what happened to James & Sarah as I suspect they headed "out west". Similarly I think Henry was James' brother and also went west.

Thanks.

[groom]

Hillingdon baptisms are on Ancestry. If you do a search in births for:  Clark baptised about 1820 Hillingdon, some do come up in London, England, Births and Baptisms, 1813-1906.  I cant see any with parents James and Sarah though.

[supermoussi]

Aha thanks Groom.   

Unless there is a gap in the online Hillingdon records, then would it be fairly likely to say that the James Clark & Sarah Welsh/Welch that married in Hillingdon in 1817 are the ones listed at Langley Marish, Bucks (their youngest daughter Louisa's Birth Cert states her mother's maiden name as Welsh) in the 1841 Census, i.e. they don't appear to have hung around Hillingdon for long?

And similarly the Henry Clark & Sarah Olney married in 1819 are the same ones listed in Amersham in 1841 (but listed as "Hy Clark")?