It means you are a long-time Brit...an original.
We (you and I, R1b's) left the Ice Age Refuge in Iberia quickly after the end of the Ice Age and you made your way to the British Isles by boat. My people, made their way to Scandanavia by land (where the 23 marker originates) and later by boat to the British Isles. 75% of the DNA in the British Isles is ancient.The western coasts have levels of DYS390-24 as high as 90%.
My dad's mother (Mrs Smith, mtDNA U5a) is related to this (Cheddar Man) 9,000 year old guy.
I rest my case. I have no known 1st or 2nd degree relatives with anything other than O positive blood type. My Y DNA clan matched very high with the Basques and Iberians.