It possibly is just noise, the movement isn't huge, all within the margins of error but on the other hand it was a feature of the last three polls conducted and all by different companies
Pollster
Con
Lab
LD
Grn
RUK
Con lead
Fieldwork
Redfield &
Wilton
34%
(-1)
40%
(-4)
12%
(+3)
5%
(nc)
3%
(nc)
-6%
24/7
Deltapoll
31%
(-1)
42%
(-1)
10%
(+1)
6%
(nc)
3%
(+1)
-11%
21-23/7
Opinium
34%
(+1)
37%
(-1)
13%
(+1)
6%
(nc)
–
-3%
21-22/7
Mark Pack