280 London Road according to this 1986 ad from The Mitcham Diary:

WISBEY’S
of Mitcham
Fruiterers
baskets of fruit made to order
We market every day
Be Wise – Buy Wisbey’s
280 London Road, Mitcham
Telephone 01-640 1125
74 The Street, Ashtead
Telephone 75219
There’s an undated photo on Merton Memories of the shop front.