The Land of Always Summer — Christopher G. Nuttall

Centuries ago, the magic left our world ... and the magicians went with it, stepping into the Gates to Mystic Albion and leaving OldeWorld - Earth - forever.  Since then, the two worlds have remained separate, until now. When they found themselves trapped on Earth, Richard, Brains and Helen befriended Janet and Steve, a brother and sister growing up in a poverty-stricken estate, and taught them the basics of magic, before discovering that sinister forces were slowly moving against them. Now, Richard and Brains have taken Janet back to Mystic Albion to study magic, while Helen and Steve remained behind to track down the rogue magicians and stop them before it is too late. But as Janet struggles to get used to practicing magic, and living in a whole new world, it becomes clear that the two worlds are not finished with each other yet, and dark forces are lurking at the edge of the gate, ready to bring them into conflict once more …