Where @cw-kid has the sensor is in the eaves of the building, It is in shadow and will not receive direct sunlight. I do not think it will need shielding.
I would like to know where did you get the plug/adapter to make your own sensor as i have a sensor lying around.
Maybe here in South Italy it’s too hot compared to you guys in UK, but the bricks here could be very hot and change the reading. So, the recommendation is to move far from the building and use a radiatior shield.