The 1841 and 1851 census for Barrhead are available for free at East Renfrewshire Council's Portal to the Past web site.
http://www.barrhead-scotland.com/Culture/history/There are very few Bairds on the 1841 census. In 1851 there is one Robert Baird, aged 26, but his birth place is Kilpatrick. There is no Charlotte Baird listed