Harry and the Wrinklies series by Alan Temperley

1. Harry and the Wrinklies

When Harry's sent to stay with his great-aunts at Lagg hall, he thinks he is in for a really dull time. But Auntie Florrie, Aunt Bridget and their elderly friends aren't quite as Harry expects them to be. Aren't they too old to be driving fast cars and climbing trees.

2. Harry and the Treasure of Eddie Carver

The brilliant sequel to Harry and the Wrinklies - another fast-paced and thrilling adventure!

When Harry wakes up in the middle of the night to find that Lagg Hall has been set on fire, he hasn't time to be terrified. He has his dog, Tangle, to rescue, and he must raise the alarm and make sure his aunts and their gang of criminal mates are safe. It's only after the fire is out that they start to think - who was it who wanted them dead.