Was there rumours they plan rejigging constituency boundaries even more in their favour
for future elections...??? Pure myth!
The reality:
The Parliamentary Constituencies Act 1986 (as amended in 2011) required the four Boundary Commissions for the UK to carry out a review of constituencies and to submit final reports to Government in September 2018. Parliament specified that the 2018 Review must reduce the number of constituencies, and therefore MPs, in the UK, to 600. It asked us, as an independent and impartial body, to consider where the boundaries of the new constituencies in England should be, ensuring that every new constituency (except two for the Isle of Wight) has roughly the same number of electors: no fewer than 71,031 and no more than 78,507.

If left as at present there is a faint possibility that the bias towards Labour in the present boundaries would create another nightmare on corbyn street,

It is generally held that constituency boundaries at present favour labour by a combination of gerrymandering and malapportionment,
https://www.geog.ox.ac.uk/research/transformations/gis/papers/dannydorling_publication_id1322.pdf


https://research-information.bris.ac.uk/files/102177649/Gerrymander.pdf
Terrible things facts (unless a guardianista)