Thank you. I had not understood what is happening and I think I do now. The NFKD is separating the í into 2 characters and the substitution is removing the 2nd one (the NonspacingMark) leaving an i (similarly for other 2). So "Lubomír,Bartoňová" becomes "Lubomir,Bartonova". Unless this is done there is no match for the combination of strings which include this name (BTW, the name is fictitious - I should have mentioned that). I am at a loss as to why we need to do this via this API which from a UK government organisation but there is no documentation saying this must be done.