LONDON (Reuters) – A wave of optimism washed over bosses of major British companies in December, ahead of a tightening of COVID-19 restrictions this month, even though many thought it would take a long time to recover fully from the pandemic, a survey showed on Friday.

The quarterly poll of chief financial officers from accountants Deloitte showed the biggest improvement in optimism since the survey started in 2007.

Still, half of the respondents said it would take at least until the end of 2021 before revenues return to their pre-pandemic levels – chiming with a Bank of England survey published this week.

“Boosted by the prospect of mass vaccination and growth, business sentiment surged this quarter with CFOs taking the most positive view on profit margins for the last five years,” said Ian Stewart, Deloitte’s chief economist.

Expectations for hiring and investment recovered in the latest survey but still remained in negative territory.

On Wednesday, Bank of England Governor Andrew Bailey said a surge in investment was critical this year to help heal the scars left by the pandemic.

Many economists believe Britain has slipped back into recession, with the BoE estimating the economy shrank by just over 1% in the fourth quarter and others predicting further contraction in early 2021.

Britain has recorded Europe’s highest death toll from COVID-19 at more than 78,000 and also saw its economy shrink by a fifth during the second quarter of 2020, the sharpest decline among the world’s seven largest advanced economies.

The Deloitte survey of 90 CFOs was conducted between Dec. 2 and Dec. 14, including respondents from 12 FTSE 100-listed companies and 44 from FTSE 250 firms.

(Reporting by Andy Bruce; Editing by William Schomberg)