"For years, we've been having great difficulty recruiting English people," said Miguel Angel Martinez, a Spanish deputy in charge of the European Parliament's multilingualism policy.
The EU Assembly was struggling to recruit native English speakers for its interpretation and translation services, he told EurActiv in an interview.
The issue has also been raised by the European Commission, which warned in 2009 that EU institutions were likely to face an acute shortage of English-language interpreters by 2015, when the current generation of officials retire.
Martinez said the skills shortage was "due to the fact that language teaching has been removed [from school curricula] during the days of Ms Thatcher because the British thought they would no longer need it."
As a result, most young people of 25-30 years of age speak English only, Martinez said, which creates problems for the Parliament's interpretation and translation services.
Language learning, he stressed, should again become a priority for Britain.
Lords call for making language learning compulsory
Britain's poor language skills are not only an issue for officials in Brussels-based EU institutions.
The UK House of Lords has recently woken up to what it describes as a "monoglot culture" which prevents British students from participating in foreign exchange programmes such as the Erasmus scheme.
"Making language learning compulsory in both primary and secondary school would be one way of increasing the UK's participation" in Erasmus, the Lords said in a report published on 22 March.
If nothing is done to promote language learning, "the UK's future participation in mobility programmes, such as the EU's Erasmus scheme, cannot be assured," they warned.
The Lords report was part of a broader inquiry into the EU's role in modernising higher education in Europe.