Theodorus Hendrikus Cornelis (Theo) Leeuwendal was born in Soerabaja in 1880. His parents had moved to the Dutch East Indies where his father took up the position as a maker of foundry casting models at the Dutch Navy base near Soerabaja. Theo was sent back to Holland in 1890 and started living with his grandparents in The Hague. He started as a trainee at Rozenburg in March 1896, age 15 and became a journeyman in 1898. In August 1901 he left Rozenburg and moved for 3 months to Utrecht where he was registered as a ceramics painter. Back in The Hague, he moved in with his grandparents again until he moved to Gouda in February 1907, for just 5 months. In June 1907 he was back in The Hague but lived no longer with his grandparents. He then moved to Oegstgeest in August 1908. There was no certainty that he worked at PZH during any other period than the 5 months in 1907 until his name appeared as a witness (with Leen Muller) when colleague Willem Mica registered the birth first his son in 1904 and then his daughter in 1905. It is noted he lived in The Hague, so he must have commuted to Gouda by train. He was registered in The Hague as a ceramics painter the whole period between Rozenburg and his move to Oegstgeest. There he worked first for De Kroon in Noordwijk and later for Amphora. In May 1909 he moved to Leiden and shared a house with Theo Verstraaten and his wife. After Amphora he moved back to The Hague in May 1910. He was registered as a messenger for a ministerial department, later changed to servant. He married in 1912 and died in 1943, age 62 when his profession was listed as a laboratory assistant.
His known oeuvre is not large and gave no good indication of his working period at PZH. A few P décor pieces could be as early as 1901 and two pieces are believed to be from 1907. It is fairly safe to assume he did work for PZH from late 1901 until at least June 1907, the latest until August 1908. Apart from the combined TL monogram in the literature we also found work signed with a single L and with a combined THCL. He is considered the designer of many PZH decors from the period.