Gen
As Gnu's post explains, I think the problem you found was that the library you have been using had only subscribed to the first edition of the Gale 19th Century British Newspapers database. When the second edition came along not everybody decided that they had the budget for a sub upgrade. As Gnu also says, Liverpool County Library is one of those with the second version -- and Wrexham was certainly omitted from the first edition. Last time I looked (admittedly some time ago now), the National Library of Wales still only had the first edition. I believe that the BL has a third version in preparation, this time in partnership with BrightSolid (the Thomson subsidiary that runs ScotlandsPeople and FindMyPast, and also not long ago bought GenesRe from ITV). See
this item published on the BBC website in May.
As to this thread more generally . . .
Edward Mostyn THELWELL married Sarah Fenwick nee Hilton in the Sept Q. of 1873 at Ormskirk, Lancashire, England.
…
All I can find about Edward is his birth June Q. 1844 in Wrexham, Denbighshire, Wales.
...
Any information about this elusive man would be very welcome
OK . . .
Forget another wife, I've just found where I've made my mistake ...
Otherwise the tree is solid.
Excellent . . .
With ref. to Gnu's Reply 16 on p.2 of this thread -- viz
[ … ]
-- the same secondary source as I cited above in Reply 30 ties Sophia Rebecca reasonably firmly into the Owen of Woodhouse family.
...
If one clicks on the name of her husband Bevis on Sophia Rebecca's own page it becomes apparent that the source used for her marriage was Joseph Morris's 19th c. collection of Shropshire pedigrees, now kept at Shrewsbury Record Office.
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Rol
...
I think Gen might have overlooked this piece of information about Edward's mother so bringing up again 
gnu
But . . .
gnu
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What did I overlook in his mothers notes? I'm really only interested in the Fenwick-Hilton-Thelwell link, not the whole lineage of Thelwell's in Wales:-)
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and . . .
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Getting a bit off topic here as I'm only interested in the union of the Thelwells with Sarah Fenwick nee Hilton.....
But it's been a real roller coaster of a ride through the Thelwells and Wales!
Ah. Right. Understood . . .
now.

And you are quite correct to say that some of us did stray off-topic, especially if one construes what you wrote in that opening post with due care and attention: "… any information about
this elusive man would be very welcome" (my italics).
But you know how it is -- on an ancestry-oriented forum, once those hounds are off the leash they just kinda assume the OP is hunting more than one generation. Basic canine instinct. So if they really get running on the scent, the boss has just got to blow that whistle loud . . . and early.

Anyway, no harm done -- it has been good exercise, and it is excellent that you too enjoyed that "real roller coaster of a ride through the Thelwells and Wales". With any luck we have all put together some Google hits for future searchers; let's hope
haec olim meminisse iuvabit.

Rol
P.S. Talking of Google et al., and in the interest of future successful search-term selection, N.B. that once you cross the Cambrian frontier it is almost invariably
Thelwall -- in the absence of typos in the source text.