Born on 26th August 2007, Arthur Thomas is the biological son of Ashley Thomas, the local vicar, and wife Laurel. However, an accidental baby-swap sees him being given to Greg and Melanie Doland, who gives birth nearby on the same day. Their biological son, Daniel Thomas, dies of cot death on 21st February 2008. Laurel's mother Hilary Potts soon starts to think that Arthur is not Greg and Mel's son, and eventually DNA tests prove this. After a court decision, Arthur is handed over to Ashley and Laurel in June 2008. Arthur then refuses to eat and Mel comes round and helps out. Eventually, Laurel bonds with Arthur, and Greg and Mel leave the village.
in 2009 Laurel believes that Sally Spode has abducted him but is humiliated when he turns up with her and Ashley having gone out for a trip. He leaves with Laurel and Gabby to Hilary's house although Gabby later returns. Arthur returns to the village with Laurel and she and Ashley reconcile after Sally is arrested. In early 2016, Arthur and Gabby learn Ashley has dementia. When Ashley builds a pirate ship play house for Arthur, Arthur cuts himself with a saw and Ashley takes him to hospital. Arthur is left alone when Ashley wanders off and ends up at Laurel's baby scan. Laurel and Ashley are told that Ashley isn't to be left on his own with Arthur and Laurel tries to hide it from him. In September 2016, Laurel gives birth to hers and Ashley's daughter, Dotty Thomas, who is Arthur's younger sister. In December 2016, Laurel tells Gabby and Arthur that they are looking at full time care for Ashley following a stroke he has. Laurel struggles to cope, so she decides to move Ashley into full-time care, upsetting Gabby and Arthur. Arthur visits Ashley with Laurel and Gabby and sees Ashley with a woman he has developed a bond with. After Gabby has a hard time at school, Laurel takes her and Arthur out of school on compassionate leave. In April 2017, Ashley is diagnosed with pneumonia when he coughs up blood and Arthur blames himself, after visiting Ashley and being sick. Laurel is told that Ashley is not responding to treatment and that the family should start saying goodbye, which she tells Gabby and Arthur. Laurel brings Ashley home for his final days and he later passes away. At Ashley's funeral, Arthur reads a poem, but runs off and tells Laurel he will never be able to make new memories with Ashley.
- Arthur is allergic to seafood and bee stings.
- Arthur's first credited appearance was in Episode 7379/7380 (24th December 2015), although despite appearing in subsequent episodes he was not credited again until Episode 7409 (27th January 2016).