Boris Johnson has denounced as “completely unacceptable” a blacklist of Irish surnames drawn up by Pontins to keep supposedly undesirable guests out of its holiday camps.

An investigation by the Equality and Human Rights Commission found that the company had been using the blacklist as part of a policy of refusing bookings by Gypsies and Travellers to its holiday parks.

Responding to the case, detailed in an EHRC report published today, the prime minister’s official spokesman said: “This is completely unacceptable. No-one in the UK should be discriminated against because of their race or ethnicity.”

The EHRC said that by declining to provide its services to guests of a certain race or ethnic group, Pontins was “directly discriminating on the basis of race” and had “breached the Equality Act”, which recognises Gypsies and Travellers as distinct racial groups.

Discriminatory practices included:

- Monitoring calls and refusing or cancelling bookings made by people with an Irish accent or surname;

- A blacklist of Irish surnames, published on its intranet page, entitled ‘undesirable guests’ and requiring staff to block any potential customers with those names from booking.

- Using a ‘no commercial vehicles’ policy to exclude Gypsies and Travellers from its holiday parks.

EHRC executive director Alastair Pringle said: “It is hard not to draw comparisons with an ‘undesirable guests’ list and the signs displayed in hotel windows 50 years ago, explicitly barring Irish people and Black people. Banning people from services based on their race is discrimination and is unlawful. To say that such policies are outdated is an understatement.”