You can now search and discover content in 2.5 million articles, 250,000 pages and growing, from Welsh newspapers free and online at http://welshnewspapers.llgc.org.uk/en/
The period covered is 1844-1910. It's a mixture of English and Welsh language content.
The search interface looks to be the same as was used by the British Library.
Although this is a beta version it appeared to work well, however I was unable to find the advanced search capability.
Find detailed information on the project at http://www.llgc.org.uk/index.php?id=4723
Impressive how the National Library of Wales, a country of three million, is capable of doing this; a national shame that Canada's Library and Archives Canada serving a population more than ten times the size, cannot. Why not?