A second trial with Kent in 1947 saw Witherden judged to be a "fair" player but one who, at the age of 26, was considered to be "too old". He was playing for
Leigh Cricket Club in
Kent and working on the ground staff at
Tonbridge School when he played his first matches for Kent Second XI in 1950. In three matches he took 19 wickets with his off-spin at a
bowling average of 13.52 and, despite his age, was taken on to the Kent staff for the 1951 season. He played as a professional for Kent from 1951 to 1955, but never established a firm place in the team. Good bowling performances for the Kent Club and Ground and Second XI teams saw Witherden make his first-class debut in 1951 against
a Minor Counties XI, taking
five wickets on debut for a cost of 32 runs (5/32) in the second innings. In the following match, Witherden made 8 and 51 against
Warwickshire at
Maidstone, and the following day scored 100, his only other first-class century, in three hours in an innings victory over
Worcestershire on the same ground. The remainder of the 1953 season saw only two more double-figure scores for Witherden as he played in nine Kent matches. He was highly successful in his first five seasons, and was the leading run-scorer in the
Minor Counties Championship in 1958, scoring 808 runs at a
batting average of 44.88, in 1959 (1,031 runs at 79.30 with three centuries) and in 1960 (855 runs at 53.43). He was also one of the leading Minor Counties bowlers in 1956. His 1959 performance was the first time a Norfolk batsman had scored 1,000 runs in the Minor Counties Championship and remains one of only 13 times the feat has been achieved and is the eighth highest season's aggregate in the competition's history. He was awarded a
benefit season in 1961, but suffered an injury to his right hand. This required an operation in 1962, meaning that he missed half of Norfolk's matches. ==Family and later life==