Howard may and most probably originated from an Ancient Germanic name.
However, Howie, may it be the nickname of Howard, probably has its root in Scotland and could possibly be originated from the Scottish name Howey. Its first documented use dates back to the 17th century. John Howie (1736-1793) is a well known author in Scotland’s history. The use of Howie could be as early as 1590. Robert Howie was recorded as being the Principal of Marischal College, Aberdeen.
The name Howie definitely has its British heritage, it was originated from Scotland and is an English name for boys.