Strange problem with cold air flow - HELP ?

[fraz]

I've just acquired Trophy and on my 300mile drive back through pouring rain I noticed the following:

Cold air enters the car from under the drivers dashboard irrespective of the airflow setting. This goes away with the fan set at 2 or the recirculation on.

Anyone have any ideas on the solution?

 

[Carbon Chaos]

Sounds like some thing is a miss in the heater box? as the recirc flap will draw air from the cabin in this area may be its not sealing correctly and fan speed 2 is enough to pull the air past from outside?