The world has heard a lot about systemic and structural problems over the past two years, mostly because of the Black Lives Matter movement.

It is rarely explained how 'structural' discrimination works, but this week's Watford Observer front page about school admissions gives an insight.

Six schools - Watford Grammar (Boys & Girls), Parmiter’s in Garston, Queens’ in Bushey, Rickmansworth School, and St Clement Danes in Chorleywood - had instituted rules meaning pupils should live in a home with a lease longer than six or 12 months, or even two years.

This was intended to stop wealthy, sharp-elbowed parents briefly moving into the catchment area to get their child a place at a good school before moving away.

Read more: Schools' admission requirements 'unfair' for pupils in rented homes

But with shorthold tenancies common among private renters, and most lasting six months before rolling on monthly, the system was loaded against anyone on a low income who rented.

Many families might not even consider the part of the form where they fill in their address and how long they had lived there as that important.

But to some, how they pay for their home and not their children's grades became a barrier to a place at a good school.

The rule might exist for a good reason, and the people drawing it up might not even realise it had that effect, but the discrimination is real.

Read more: Homes approved despite accusation plans will 'scar historic neighbourhood'

After a complaint and an investigation by the Office for the Schools Adjudicator, Adjudicator Tom Brooke said the schools’ admission arrangements did not comply with the School Admissions Code, which states authorities must ensure the allocation of places is "fair, clear, and objective".

It is reassuring that the six schools have reacted positively, pledging to ensure genuine local applicants were not denied a place.

Fraudulent applications need to be stopped and restrictions like minimum tenancy agreements can help.

But it should never come at the expense of pupils from poorer backgrounds who might really benefit from the education they receive at one of Watford's great schools.