Above is good shout. Lhs could also be your aerial. Check around the base of it to make sure it's not corroded and still sealing etc. Check your entire boot aperture seal for any knicks or tears. A good way to identify the problem area is using a garden hose or watering can and dowsing each area individually, then checking to see ingress. If you have a small person, put them in the boot with a torch while you do it