I wondered if anyone has come up with an ingenious idea to disguise them.

More lazy than ingenious - but it works for me. Take a plant pot (about 4 or 5"
size), paint it white to encourage reflection of any direct sunshine. The holes
in the bottom of it provide a degree of ventilation. Wedge the sensor inside,
with pot on side (keeps rain out). You now need an evergreen but well
ventilated hedge - that might be the tricky bit! - it is important to keep
sunshine at bay and to keep it (pot) away from any surfaces that may absorb
heat in the daytime and release it at night. Insert pot on its side into
aforementioned hedge / evergreen tree.

A better alternative, advocated by others on this NG, is to buy a set of round
drip trays that you normally but flower pots in. Assemble into a vertical stack
(with rods), allowing a gap between each one, cut out middle of all but the top
and bottom ones - to make a shaded but ventilated cavity - paint white and you
have a homemade screen that should be food enough to sit in the sun and not
'overheat'.. Apols for having forgotten who came up with this idea - I remember
a link to a webpage. Hopefully he/she will respond later. That was a bit
advanced for me!

The important thing is to get a sense of how your temps should compare with
nearby sites. If you reveal your location, I am sure NG members will help to
comment on any temperatures you record and to discuss how your site might be
expected to compare with local official sites. .

Julian Mayes, West Molesey, Surrey.