Croydon and Sutton is a constituency that elects one member of the London Assembly.
The seat has been held by the Conservative Party since its creation in 2000. Andrew Pelling was the assembly member from 2000 - 2008.  He was succeeded by Steve O'Connell, who is the sitting member. 
The Wikipedia page is [https://en.wikipedia.org/wiki/Croydon_and_Sutton_(London_Assembly_constituency).