Watford have confirmed the signing of the former Arsenal forward Danny Welbeck on a free transfer, kick-starting what is expected to be a busy final day of the transfer window. The 28-year-old England international has agreed a contract after finally joining a club that had first enquired about him a year ago, when they were quoted a fee of £8m.

Welbeck, who signed for Arsenal from Manchester United in a £16m deal in September 2014, has not played since last November, when he sustained a serious ankle injury half an hour into a Europa League tie against Sporting.

It was the latest in a string of serious injuries for a player who was restricted to a total of 20 league starts in the 2015-16, 2017-18 and 2018-19 seasons combined. He has been working on his fitness through the summer and, having passed a medical on Tuesday, will immediately join the first-team squad although, given his lack of match practice, he may not be considered ready for the club’s first game of the season at home against Brighton on Saturday.

The signing brings to four the number of England internationals on Watford’s books, with Welbeck joining his former Manchester United teammates Ben Foster and Tom Cleverley and the former Chelsea midfielder Nathaniel Chalobah.

It is the Hornets’ third first-team signing of the summer, after the £5.5m defender Craig Dawson and the 19-year-old midfielder Tom Dele-Bashiru, who arrived from Manchester City on a free transfer. They also hope to complete a deal for the Rennes winger Ismaïla Sarr, with the two clubs close to agreeing a fee for a player rated by his club at £30m, £12m above the club record paid to Burnley for Andre Gray two years ago.

Watford have, however, become frustrated at the glacial pace with which the negotiations have been progressing and there are concerns that Rennes will prolong them until the 11th hour in the hope of receiving a higher offer from another club either in England or elsewhere – and potentially beyond the closure of the Premier League’s transfer window on Thursday night.