Mr Siddiqui was the father of Tariq, Trudi and Naseem Siddiqui. He only appears in Series 7 Episode 11, but is frequently mentioned throughout the rest of Series 7. His wife, Samia, passed away just under a year prior to Tariq and Trudi's first day at Waterloo Road.
Mr Siddiqui is only seen when he accompanies Tariq and Trudi on the minibus into school on their first day. He encourages them to forget about Tariq's criminal past and to see Waterloo Road as a clean slate.
Later in the series, Mr Siddiqui tries to set Trudi up with a man called Haris, whom he wants her to marry, but she fails to develop any feelings for him, as she is in love with Finn Sharkey, whom Tariq and presumably Mr Siddiqui disapprove of.
Mr Siddiqui is mentioned again in Series 8 when Tariq sends a video message to Trudi before attempting suicide, in which he tells her to "look after Dad and Nas".