The Watford transfer merry-go-round has begun with a Scotland international due to arrive and the club set to receive some much-needed cash for two outgoing Hornets.

The Watford Observer understands Aberdeen captain Scott Severin will sign for the club on a free transfer and Lee Williamson will be joining Theo Robinson in leaving Vicarage Road.

Williamson has signed for Sheffield United for around £500,000, although the two clubs refused to disclose the figure.

However, Watford have confirmed they rejected a bid from a Championship club for goalscoring midfielder John-Joe O’Toole, also believed to be the Blades.

New signing Severin will add experience to the Watford squad.

He has not been part of recent Scotland squads but has made 14 appearances for his country and played 40 times for Aberdeen last season.

The 30-year-old midfielder, who can play in numerous positions, started his career at Hearts, making 175 appearances, before switching to Aberdeen in 2004.

Severin’s arrival may not be announced for a couple of weeks but we understand everything has been completed and his arrival was welcomed by the in-coming manager, believed to be Malky Mackay.

Williamson’s departure to Sheffield United was set to be announced as we went to press but Robinson’s move to Swindon Town is unlikely to be concluded for at least another week as the striker is out of the country.

The 20-year-old had a choice between Swindon and Brighton & Hove Albion, who both offered around £200,000 for the striker, a fee which could rise to £275,000 with additional add-ons based on appearances and promotion.

Southend United, where Robinson scored seven goals in 21 games while on loan this year, were interested in the Birmingham-born striker but could not afford to match the figure.

The transfers are the first of many expected at Watford and chairman Jimmy Russo said: “There will be other players leaving and new arrivals and we will have a squad the size the manager requests, within our budget.”

Former Watford manager Brendan Rodgers is believed to be considering a move for talisman Tommy Smith and defender Mike Williamson, who the ex-Chelsea Reserve team boss only signed in January.

Russo said: “I have made it quite clear that any approach for any of our players must come through the club.”