The RHS site is supremely helpful, but I have found that there have been a number of grexes that I have not been able to find the names of using the parents. This being before I have found out the name of the grex - and have had to look through pages and pages of internet searches to find a possible name - then, when I put the grex name in it gives me the exact parents as I put into the original search. Very odd. I keep meaning to email them when I have this happens to me, but never get round to it.