Wow..... Looks like maybe its the very very old self spacing Durastone I think, as I don't remember the Kerastar being self spaced..... its been dead for at least 18 years. Closest range now will be the Dorset Wooliscroft Stone (Also finished when Pilkingtons went down the pan in 2010.) But the range was pretty popular so after a few years when all the old stock was gone, Original style started to make them (or have them made) again.
Downside is that the size is 2mm smaller and 1mm thicker (148x148x9). So not perfect but the closest I imagine you will get now. The Dorest Quartz may also be a close colour but this has a slightly pinkier hue to it.
Versatile smooth surface Anti Slip Tile | Dorset Woolliscroft
Hope this helps