Hi EC
The only Thomas Randles, described as a Miller,in 1851 is as follows:
Living at Mill, Llanymynech, Mtg.
Thomas Randles (48) miller, b. Kinnerley, Salop
Elizabeth Randles (44) his wife, b. Trefonen, Salop
Children: James (19) b. Trefonen, Thomas (17) b. Trefonen
John (12) b. Trebach, Salop, Samuel (9) b. Trebach, Ellen (6) b. Llanymynech, Mtg.
Bearing in mind Rosamond Randles married in 1837, 14 years before this census, casts some doubt on whether the above are her parents and siblings.
Living at Trederwen, Llandrinio
Richard Jones (79) wheelwright, b. Shrewsbury, Salop
Mary Jones (70) wheelwright, b. Llandrinio, Mtg.
Robert Jones (29) wheelwright, b. Llandrinio
Tryphenah Jones (28) his wife, b. Llandrinio
their children, James (

, Thomas (6) and Alice (3) all born Llandrinio.
Unfortunately I cannot find either of these families on the 1861 census. It appears that this area may have come under 'Salop' in 1861, and therefore a look-up in the Shropshire 1861 census may prove useful.
Good luck
Stan.