Stored procedure doesn't return expected result.

I'm writing a script to clean up some data in a table, the data I'm
using as the source is held in emails, so I've written a perl script
to extract the info. Unfortunatly this email doesn't contain the
client id, so I've written a stored procedure to extract it.

create or replace function get_client_id(text) returns integer as $$
SELECT intclientid FROM client WHERE vchname = '$1';
$$ LANGUAGE SQL;

However, when I do this:

select get_client_id('Stuart Grimshaw');

I get no results, yet:

SELECT intclientid FROM client WHERE vchname = 'Stuart Grimshaw';

Gives me the result I would expect:

 intclientid
-------------
           3

What am I doing wrong in the stored procedure?

--
-S
http://www.makepovertyhistory.org/