Celtic's first summer signings of last 20 years including former Newcastle United, Aberdeen and Man City stars

The summer transfer window looks set to be a busy one for Celtic as Brendan Rodgers looks to build on the momentum built by his side’s domestic double win.

There are big decisions to be made in key areas of the Hoops squad after goalkeeper Joe Hart confirmed his retirement last month and popular loan signing Adam Idah has now returned to parent club Norwich City after helping Celtic to a Scottish FA Cup Final win against Rangers.

Retaining the services of in-demand midfielder Matt O’Riley will also be of paramount importance for Rodgers as the Denmark international continues to attract attention from several clubs in the English Premier League and around Europe.

There will also be a need to add to the Celtic squad as Rodgers looks to guide the club to success on a number of fronts over the course of next season. With the transfer window set to open, we take a look at which players were the first through the door at Celtic Park in each of the 20 summers.