Your knowledge of Ipswich and it's traffic control systems is impressive and most likely unrivalled. Chapeau.
Fortunately for me I live near what i consider to be the best lights in the town, every town needs one redeeming feature and Ipswich's is this particular set of four way traffic lights.
They are radar / motion sensor operated and will pick up a car or cyclist from quite a distance. During quiet periods, it is possible for them to turn red and then back to green ready for safe and unimpeded passage without the need to slow.
Don't keep us in suspense! For those of us who know Ipswich where are these magic lights?