The Middle Temple register of admission begins July 1501. Admissions prior to July 7, 1501 are listed in a reference titled: "Register of Admissions To The Honourable Society Of The Middle Temple", by MacGeach and Sturgess, Vol.I, 1949. Most of these early folks are listed by surname only with the earliest recorded in 1451.
The first admitted with the surname JONES is William Jones, 1565. As listed it states: "Nov. 24, William Jones, son of John Mirydeth of Bergevennye, Monmouth, gent." (p. 30)
This record again demonstrates the complexity of the surname for those of Welsh descent. Here William Jones is the son of John Mirydeth (Meredith). He has taken the surname JONES as William "son of John" who is listed with the surname "Mirydeth". Thus, in this case, the William Jones is connected to the Meredith family by DNA, not surname. In the next two to three generations, this becomes apparently two distinct surnames, and may be lost in the JONES family tree climbing.
Reference: Register of Admissions To The Honourable Society of The Middle Temple, From the Fifteenth Century to the year 1944, Vol. I, compiled under the Direction of the Deputy Treasurer, Sir Henry F. MacGeagh, and the Master of the Bench by H.A.C. Sturgess, London, by Butterworth & Co., LTD, 1949.