Thank you nvmof3 and affleckservices for your advice.
My husband booked a gutter cleaning service for next tue. Hope it will be sorted. Definitely we will follow your blog affleckservices to have the gutters checked regularly.
Best wishes!

Sounds like a blocked gutter. Do you have a ladder? If so, easy to sort out yourself.

Dear readers,
We got home today found there is a strip of very damp mark from the top to the bottom of one side the kitchen wall. Like 10cm wide! Happened in only a few hours while we were out today. Clearly is from the rain. There is no water dribbling from inside. Can anybody advise us who should we call to have it checked up? Gutter specialists? Or builders? Never experienced things like this. Really appreciate some help here. Big thank you in advance!