I took a closer look at my rear tire this morning, and found a healthy assortment of slight cuts, but also the thread starting to peek through the rubber.
So, the cheap Vittorio Zafiro's have reached end of life after about 5500 km - not too shabby from a £10 tire.
Got some similarly cheap replacements off Billy Bilsland at below MSRP - here's hoping they will last a similar distance.