VLOOKUP to return highest result value

I have a list of names on sheet 1, column B and a list of numbers in column I. Names can appear more than once in column B with different dates in columm I. I want VLOOKUP to find the name in B and then return the highest result.

EG, lookup 'Sam' in the list below should return 1 June 2012;
Sam 2 Jan 2012
Bob 19 May 2012
Sam 1 June 2012

I'm currently using this:
=VLOOKUP(BH16,'1'!$B$16:$I$300,5,FALSE)
..but it is returning the first result it finds, not the highest.

Any help would be appreciated, thanks!