Shoppers queueing outside Selfridges

LONDON — Security is being tightened across London and British police are on high alert for a terrorist attack as millions of shoppers head to the city’s center today to take advantage of the annual Boxing Day sales.

London’s Metropolitan Police said following the events in Ankara and Berlin, an attack in the British capital is highly likely, and measures have been upgraded.

“As a matter of routine, as a precaution, we review our plans after attacks overseas, and we are doing so at present following the awful incidents in Berlin and Ankara. The Metropolitan Police has detailed plans for protecting public events over the Christmas and New Year period,” said a Metropolitan Police spokesman.

“These [plans] already recognize that the threat level is at ‘severe,’ meaning an attack is highly likely, and [we] have considered a range of threats, including the use of large vehicles.”

New measures include the addition of more undercover forces across busy shopping thoroughfares, such as Regent and Oxford Streets, and at Westfield shopping malls in Shepherd’s Bush and Stratford.

Boxing Day is one of the biggest shopping days of the year in Britain, with stores unveiling major markdowns as they seek to clear inventory.

Concrete barriers have also been added across Trafalgar Square, where crowds traditionally gather to watch the New Year’s Eve fireworks.

Security measures are being reviewed in other cities across the country. In Birmingham, the city’s main Christmas market has been surrounded by concrete barriers, and there is an increased police patrol in the area.

In addition, Police Scotland has confirmed it will be increasing the number of armed officers across Edinburgh from 275 to 400, to protect the 150,000 citizens participating in the city’s New Year’s Eve street party.

Despite the increased terror threats and post-Brexit instability, which has seen the pound hit lows against the dollar and euro, a record 14 million shoppers are set to take part in Boxing Day sales.

The New West End Company, which represents central London retailers, expects spending to reach 55 million pounds, or $67.6 million, following the uptick in shopping due to the weaker pound.

Jace Tyrell, chief executive officer of the New West End company, said the projected increase in spending is due to international shoppers taking advantage of both the bargains on offer and the weak pound.

“This year promises to be especially strong for retailers, as visitors from around the globe make the most of the deals available…combined with the relative value of the weak pound. We expect a significantly higher number of Chinese tourists to come over specifically to bargain hunt,” said Tyrell.

Shoppers were seen queueing from 11 p.m on Christmas night in the West End, ahead of the sales.

Selfridges said during its first hour of trading, between 9 and 10 a.m., it generated 2 million pounds, or $2.5 million, across its web site and four U.K. stores. The site logged one million visitors, its highest number to date, with 75 percent of transactions done via mobile.

“The customer response to the sale in each of our stores so far today has been unprecedented, with top sale items going quickly. We are on course for another record-breaking Boxing Day opening,” said store director, Meave Wall.

Data from the U.K.’s Office of National Statistics highlighted exceptionally low levels of household savings, as well as a 0.3 percent growth in the fourth quarter of 2015, due chiefly to increased consumer demand in the retail sector.

Despite weak income growth in British households, the data suggested that U.K. consumers are concentrating their spending in 2016, ahead of expected price increases next year.