UPDATE 2 December from David Russell, Roads Manager at LES via John Letford:

Following the last flooding event at this location, an extensive investigation was undertaken to ascertain the cause of the flooding.  Previously, the cause was thought to be fallen leaves covering the gully grates forcing water to accumulate at the location.  However, the investigation indicated that there was a partially collapsed carrier pipe which channeled water from the roadside gullies to a manhole in the central reservation and, from there, into the surface water sewer.

Consequently, works were undertaken to repair this pipe and these are now complete and no recurrences of further flooding has been noted. Notwithstanding this fact, my engineer will continue to closely monitor this location in order to ensure that this situation remains.

this from Councillor John Letford:

Work is currently underway at Great Western Rd at the Pond. Land and Environmental Services (LES) have dug 2m down and found a blocked pipe, which has now been fixed. Hopefully, when the work ceases, the continual flooding also ceases.