This equipment in the high voltage (HV) side of the substation appears to be the main breakers (switches). The smaller units to the left appear to be for “Wimpson Lane flats, Tee Walnut Grove” and Timsbury Drive. The equipment in this side of the substation was owned by the electricity supplier (SEC, later SSE). It is likely they used space in the OS substation to serve these neighbouring properties rather than them having a dedicated substation. The first one of the larger units is used metering and the next five for each of the four transformers (there were only four transformers so the middle one was unused but having an extra breaker meant that an extra transformer could have been installed if necessary). I think the one on the far right may have been related to the chillers.