He has a strong upper class British accent. Totally believable and not a trace of American English.
His vowels are the strongest element with clearly defined open syllables and plosives “t”s (where an American would either miss them out all together or give a “d” sound).
I am truly impressed with his articulate British accent!
As for a van Dyke accent, Which was a poor attempt at Cockney this is nothing like it, And in a different league altogether.
The fantasy series "Game of Thrones" might be a drama with dragons thrown in, but one thing keeps it grounded: the authenticity and commitment of each actor to their craft. In the case of Peter Dinklage, this comes out in his accent. He might be the only American lead on the show, but you'd never guess that when you tune in each week: his British accent is pitch-perfect.
I'm a huge Game of Thrones fan, and I think the acting and the accents are both great. I've never thought that Peter Dinklage's accent was not believable on the show. He blends right in, which is the best sign of a good accent. He's an excellent actor, and the people who are complaining are probably just jealous.
I do not watch Game of Thrones but I have seen clips and heard a lot of great things. As far as Peter Dinklage goes he is an exceptional actor and I believe he has a believable accent. A true actor can become a role and I feel that Dinklage has that power as an actor.
He sounds like an American trying to do what he thinks is a British accent, Which of course is what he is. Dick van Dyke in Mary Poppins all over again. However, It's his trade, He should have made more effort, And I'm surprised as he is otherwise a great actor.
As iconic a character as Tyrion Lannister is in "Game of Thrones", Peter Dinklage's accent when playing him tends to fluctuate between his native American accent and an overly-forced RP accent. The pronunciation of the word "can't" tends to have an overemphasis on the vowel sound. In the first season, he was still getting used to the role, but has become better over time.