New Fantasy story about the quest for the holy grail

The book is known as The Traitor’s Sword in the UK (where it has been out for some time) and The Sword of Straw in the US (where it is published this month). The two titles do refer to the same sword, which is of course the same magical artifact from the Grail legends, completely re-interpreted for Hemingway’s Arthur-less (and indeed Camelot-less) grail story. Having secured the Cup, young Nathan now has to travel to a different parallel world to secure the Sword. Along the way he gets to meet and fall in love with a princess, but one who shells peas rather than one who tries to avoid sleeping on them. Meanwhile, back in his own world, the bad guys continue to chase after Bartelmy Goodman to try to steal the Grail. And even Barty, who is after all a kindly old wizard, is well rooted in everyday things.