Syr William H. Preece 1934-1913. Cofeb i’r gwr hynaws am ei waith fel arloeswr gyda telegraff diwifr. Hefyd yn arbenigwr gyda Marconi. Yma ym Mhenros bu ei flynyddoedd olaf. Bu farw 6 Tachwedd 1913. In memory of the above for his pioneering work on wireless telegraphy. He lived at Penhros until his death.

English translation: "Sir William H. Preece 1934-1913. A memorial to the gentleman for his work as a pioneer with wireless telegraph. Also an expert with Marconi. Here in Penros his last years. He died on 6 November 1913. In memory of the above for his pioneering work on wireless telegraphy. He lived at Penhros until his death."
Siaron James from Caernarfon, Wales on Wikimedia Commons
See also...
Elliott Brown on Flickr