LONDON -- The U.S. ambassador to Britain is not, it seems, afraid of a mouthful of consonants.

Before the NATO summit that kicks off Thursday in Newport, Wales, Matthew Barzun tried speaking the oldest language on these British Isles and tweeted the results in a good-natured video in which he concedes his Welsh needs “improvement.”

The Welsh gave him a thumbs up for his efforts, which included tackling the tongue-twisting “Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch” -- a village in Wales that boasts the longest name in the United Kingdom.

Robin Farrar, chair of Cymdeithas yr Iaith Gymraeg, or the Welsh Language Society, said: "'Chwarae teg' (fair play) to the U.S. ambassador for giving it a go.”

The news site WalesOnline. said they were “delighted” to see the ambassador attempting to speak Welsh, but observed it took him no less than nine attempts to nail the word “Helô". Welsh language experts said that Barzun didn’t mangle the tricky “ll” or “ch” sounds too badly, but for anyone wishing to learn more summit-friendly phrases with a bang-on accent, The Post offers help here.

Like rugby or their celebrated male choirs, the Welsh language is a hugely important part of Welsh identity and is widely displayed, even though it’s spoken by just 1 in 5 people in Wales. Visitors to the summit will notice bilingual signs everywhere (translation mishaps on road signs are more common than you might think -- this one being one of the more amusing.)

Despite historic attempts to discourage the Welsh language -- for instance, in the 19th century some Welsh schoolchildren were punished with a “Welsh Not” for speaking their mother tongue -- the language has stubbornly survived. Since the Welsh Language Act of 1993, the devolved Welsh government has passed various laws to help promote the language, including making it a compulsory school subject for children up to age 16. Although official figures have shown a dip over the past 10 years in the population speaking Welsh -- from 21 percent to 19 percent -- it’s still more popular than other Celtic languages, including Irish, Scottish Gaelic and Cornish.

For his part, Barzun has proven himself wrong: There are Americans who know more Welsh words than just Catherine Zeta-Jones.