I think Lucy confessed during her trial to her defence team here's why.

Fact - Lucy didn't call any witnesses (Apart from the plumber)

Fact - Lucy has witnesses lined up and they were stood down at the last minute.

Fact - the witnesses were confused why they were stood down

Fact - we don't know why this occured but this was at Letbys request.

Theory - she confessed to Ben Myers at some point during the trial.

Lucy insists on maintaining a not guilty plea despite confessing to their legal team, her solicitor or barrister faces ethical constraints. They cannot knowingly allow her to present a false case or call witnesses to support a defence they know to be untrue.

They allow her to present the case but will not actively support or elicit false evidence from witnesses. This means that their strategy was:

Challenge the prosecution’s case on technical or procedural grounds, even if the defendant has confessed. For example:

Arguing that the prosecution has not met the burden of proof (beyond a reasonable doubt).

Highlighting inconsistencies or weaknesses in the prosecution’s case.

they had a focus on the prosecution’s failure to prove its case.

Perhaps this was the only way the defence felt they could get a not guilty plea? And why doesn't Mr Mcdonald know why they called no witnesses.

Please tear my theory apart