Some DNA databases including the GREGORY surname:

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Halifax Co., VA DB 6:396 21 May 1767 William Powell & Elizabeth his wife of Co. of Halifax & Thomas Gregory of other part, 40 pds, south side of Bannister R., 200 acres, part of patent granted to Wm. Powell 13 Aug 1765, 294 acres, Reads line, Davises, Bannister Riv., Bye Cr, Mowrays line.  Wit: Jonathan Williams, Luke Williams, & G. Dickeson Junr.

I have nothing to relate the below Thomas Gregory to the Thomas Gregory of above Halifax Co. deed.  However, I don't have information on a Thomas Gregory in Mecklenburg at that time.  One Thomas Gregory shows up in Mecklenburg Co., VA as a witness the year following the above Halifax Co., VA deed:
Meck. Co., VA DB 3:517-519; 6 Jan 1773; 11 Jan 1773, Ephraim Mabry of Meck. to John Speed, Junr of same, 35 pd, 373 acres both sides Flatt Creek in the co of Meck begin at Twittys.  Prov. by the oath of the witnesses: Samuel Bugg, Howell Collier, Thomas Gregory, Joseph Speed.
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Meck. Co., VA DB 4:77,78; Jan 1773 (same date as above); 14 June, 1773 (prov. different date from above), William Allen of Co of Meck to Charles Duncan & company admr of Abraham Whittemore Senr dec'd, 118 pd, one shill & 6 pence, which sd William Allen  is justly indebted to the said Charles Duncan & Co...tract of land in co of Meck, 200 acres, beginning at mouth of Mountain Creek on white oak then short distance to spanish oak on Meherrin R., Andrews corner, Arnolds line, also 4 negroes;  Prov. by the oath of the witnesses: Lewis Parham, John Lucas, Thomas Gregory.

WILLIAM GREGORY : No. S1666; NC 22,145 West Tennessee:

William Gregory, Smith Co TN, was a private in the Corps comm. By Capt. Hern of the regt

comm. By Col Clark in the NC mil for 8 months.

1832 Smith Co TN: William Gregory, a resident of Smith Co TN, aged 68 years last May; that

in the month of Nov 1780 Chatham Co NC he entered as volunteer…he has no written discharge nor never received any or amy other documentary evidence by which he can prove his service except Isham (?) and BRY GREGORY whose testimony he offers..s/William Gregory.

Isam Busby aged 73 years, well acquainted with Wm Gregory in Chatham Co NC at the commencement and through all the war...s/Isham Busby

Sept 1832 Smith Co TN: BRY GREGORY a resident of Smith Co aged (ink blot) says that Wm Gregory is his brother and that he knows he did enter the services as a volunteer under Capt. Hern in Orange Co NC and served his tour….s/BRY GREGORY

15 May 1939: letter to CLAUDE GREGORY, 5590 Guilford St., Detroit Michican, from A. D. Hiller Exec. Asst to Admin:…WILLIAM GREGORY was born in the month of May 1764…brother of the soldier, BRY GREGORY, was living in 1832 in Smith Co TN. It is not shown that the Capt. GREGORY under whom the soldier WILLIAM GREGORY served in 1780 was a relative…" Gregory Revolutionary War Pensions

GREGORY, BRY : NC: S.2249; 3 Sep 1852 Smith Co TN; personally appeared in open court before John CHAMBERS, Zackary FORD, and Isaac GOODALL for the court of Pleas on a Qarter session now sitting, BRY GREGORY resident Smith Co TN; that he entered the service of the US under Capt. PATTERSON 1780; from sickness was furlowed and as he recovered his health in a few days he left home for Capt. PATTERSON's co and fell in with Capt. Dudly REYNOLDS co and served in his co 3 months and then rec'd a written discharge which has been lost. Afterwards in the year 1781 he volunteered again under Capt. Benjamin HERRIN, marched to Gen. LILLINGTONs camp, and served under him until discharge making a 3 month tour; that he volunteered both time in Chatham Co NC being a resident of sd county and state, was in the battle of Cane Creek in the time of his last 3 month trip, served Gen. BUTLER and COX afterward in the year 1782 he volunteered in Chatham Co NC under Capt. Alex. CLARK*, marched to Caine Creek and then had a battle under Gen. BUTLER and Col. LATERAL, then he persued the enemy to Ross Swamp then returned back to Cross Creek and there remained until discharged serving 3 months more. The war closed about that time, making in all 9 months service. He has no written discharge nor - for the 2 last services, nor has he any other documentary evidence by which he can prove his service nor does he now know of any person by whom he can prove the same except WILLIAM GREGORY.s/BRY GRIGORY X his mark. Wit: Miles WEST a clergyman and Isham BEASLEY of Smith Co TN certify.

3 Sep 1832 Smith Co TN; WILLIAM GRIGORY res/o sd Co aged 69 years says that BRY GREGORY is his brother and that he knows he did enter the service as a volunteer under the - as stated above and served as he has stated. s/WILLIAM GREGORY.

letter to Mr. W.L.GREGORY, The Plaza Bank of Saint Louis, MO dated Apr 1939, from A.D.Miller Exec Asst to the Admin, in answer to rev. record of BRY GREGORY and 4 Apr 1940 to Mr. Claude GREGORY, 5590 Guilford St., Detroit Michigan..."in 1843 (BRY GREGORY) address was care of Maj. W. H. Wilkerson, Pleasant Shade TN; he died in Jan 1846, place of death not shown".

* Note upon close inspection of the original documents it can be seen this may be Clardy Gregory Revolutionary War Pensions