It’s thought a faulty update to widely used cybersecurity software is to blame for an outage that has affected businesses worldwide – including banks, airlines, train companies and TV and radio broadcasters.

Heathrow says its flights are operational and contingency plans are being introduced to minimise any impact on journeys.

The airport is asking people to check their flight status before checking in.

Today is thought to be the busiest day for aviation for 5 years since before the Covid-19 pandemic outbreak.