The first name that comes to my mind is that of Nicolas Jones.
Nick is from Cardiff and is 13 years old. He'll turn fourteen later this week. It'll be really good to see a Welsh player doing well.
He's the only 13 year old Brit in the top 700 of the U16s. He's ranked 103 in the U14s. Of course, no younger Brits are ranked ahead of him. Although he is certainly behind other 13 year olds from different countries, like Carlos Boluda, he shouldn't worry. Because Boluda will either either reach the highest levels of professional tennis and win Grand Slams or else the success will get into his head and he will be ruined.
Nick did an interview with BBC Wales before some time. Link.
He did really well to win the British U14 championships
, held in Bournemouth last month. He was the seventh seed but defeated older and higher ranked players on his way to the title.