At various times, Southend Transport have hired buses to assist with a vehicle shortage, often when deliveries of new buses were delayed (although sometimes it was in order to free up ST buses to hire out to other operators!). In 1973, Ensign provided ex-Portsmouth STP996. It was generally only used on peak hour workings and never acquired Southend blinds.
STP996 was a Leyland PD3/6 with Weymann H36/28R body, fleet number 124, part of a batch of five new to Portsmouth Corporation in 1959. During the 1950s, Portsmouth Corporation arranged for the registration numbers of each batch of new buses to end in 999 - not sure why ! Buses Illustrated for November 1959 reported the arrival of Portsmouth's first PD3s noting "innovations for Portsmouth include sliding vents, buzzers upstairs and bells below, and sliding cab doors".

Photo taken by Richard Delahoy, Thursday 15 November 1973, outside SCT Garage, London Road, Southend