Stored Procedure: Truncation of a nvarchar when being added to

A quick SQL Server 8.0 question

I have the following test stored procedure :

CREATE PROCEDURE  sp_testproc
AS
declare @varSQL   nvarchar(1000)
    SET @varSQL = 'SELECT BranchSortCode, BranchName, Address1, Address2, Address3, Address4, Pcode FROM BranchFile WHERE 1=1'
    SET @varSQL = @varSQL + ' ORDER BY BranchSortCode'
    EXECUTE(@varSQL)
GO

in debug when stopped at execute line

@varSQL = N'SELECT BranchSortCode, BranchName, Address1, Address2, Address3, Address4, Pcode FROM BranchFile WHERE 1=1 ORDER BY BranchSortC'

and has a type of nvarchar(130)


Why is the variable varSQL being truncated when its size is 1000 ????

Thanks.