IT was a case of so far, so good as Britain began its first full week of life as a post-Brexit country.

By early evening no major incidents or trade hold-ups were reported at the border. It is thought that many hauliers have delayed their cross-border shipments to see how the new rules are settling in. This time of year is, in any case, reasonably quiet in terms of traffic.

Yet there was something of a reality check for some British travellers as the country began life outwith the EU.

The Dutch authorities refused entry to the Netherlands to more than a dozen Britons at Amsterdam’s Schipol Airport. As members of a non-EU country they are now no longer exempt from the bloc’s Covid-related restrictions on non-essential travel.

A police spokesman pointed out all the UK passengers had a negative Covid test but explained: “They forget the basic rule, that it must concern a necessary trip; for example, for work or due to serious private circumstances.

“People from a safe country such as Australia or Singapore are also allowed to pass but the UK is certainly not a safe country.”

British citizens who have tried to return to homes on the continent have been stopped from boarding pre-booked flights because the airlines insisted they did not have valid proof of residency as their identity documents no longer applied post Brexit.

Nine Britons flying from London Heathrow to Madrid were left “distressed” after being told by airlines that they did not have the correct residency papers.

However, it emerged this was a mistake as UK and Spanish authorities had previously agreed existing paperwork would be enough to allow them to re-enter the EU once the transition period ended on December 31.

The UK embassy for Spain took to social media to explain: "This should not be happening. The Spanish authorities have reconfirmed again this evening that the green residency document will be valid for travel to return to Spain as stated in our travel advice."

The Spanish Foreign Office referred to an “isolated communication problem” and things were now proceeding normally.

A Foreign Office spokesman added: “We have worked closely with the Spanish Government to resolve these issues.

“The Spanish Embassy in London has re-confirmed today that both the green residence certificate and the new residence TIE card are equally valid in terms of proving residence in Spain, as set out in the Withdrawal Agreement.”

A small number of Britons were also blocked from entering Germany over similar residency paper issues.

Since last Thursday night, UK citizens travelling to the EU have had to show: they have a valid reason to travel; can no longer use fast-track passport control lanes; have at least six months left on their passport; show a return ticket; prove they have enough money for their stay and have their passport stamped.

On the EU border between Britain and Ireland there was a slow but steady build-up of freight movements, said Tom Talbot, head of customs operations for Dublin Port. Northern Ireland, of course, remains within the EU single market for goods and applies EU customs rules at its ports.

“This has provided a good opportunity for ourselves, for trade, for business to build familiarity with the system, with new procedures,” explained Mr Talbot.

“It allows firms to build familiarity with procedures that apply to trade and new trade with Great Britain and the arrangements that are in place across both Rosslare and in Dublin Port.

“Even for businesses that are familiar for a number of years with dealing with third-country trade, the fact that this trade never arises on roll-on and roll-off traffic is a new feature.

“We are now into a much more time-sensitive case and this is moving things a little faster.”

He pointed out that customs issues that did arise were being resolved as quickly as possible by all agencies.

“To date there has been really good engagement with both trade and business and that will continue to ensure that smooth flow, and I am confident that will continue in the days and weeks ahead,” added Mr Talbot.

Meanwhile, some online retailers across the EU have warned they will no longer ship goods to Britain because of the extra red tape and higher costs being charged by UK authorities to comply with new VAT rules.