The fact that you get the tingles with the main switch off means that your own installation is pretty much guaranteed not to be the cause. Post 2 by
@pc1966 hits the most likely nail on the head, a difference between the incoming CNE voltage and local true earth. When you felt the tingles, were you standing on a concrete floor?
That cable from the meter box is utterly bonkers. Are you sure it was the DNO who installed it and not someone whose experience is in 'loft-based horticulture?' Armour floating, unsheathed cores exposed, Inadequate support, possibly no SF for >3m, and the minor detail of missing out the meter. Did one guy do the outside end and another the inside, so that they each thought the relevant meter was at the other end? I'm at a complete loss to explain it otherwise.