The 1983 Christmas episode, the only one in which Del's father makes an appearance, and the last onenote to feature Grandad. First broadcast 25 December 1983.
On Christmas Day, the Trotters are watching TV when a stranger appears at the door. It's Del and Rodney's father (and Grandad's son) Reg, who left them 18 years earlier after the death of their mother. Del wants him out, but the other two want to give him another chance. Reg tells them he's been living in Newcastle, and has recently been diagnosed with a hereditary blood disorder.
Del and Rodney quickly take blood tests, which both turn out negative when they receive their results, but Grandad notices on their results that they have different blood types. Del and Grandad thus both assume that Rodney has a different father. However, Reg — having checked his own and Grandad's blood groups — reveals that it is in fact Del who has the alien blood group.
Reg moves in permanently and starts wearing Del's clothes, spending time with Rodney and taunting Del. On New Year's Day Rodney reassures his brother that children with the same parents can have different blood groups and recommends that he visit Dr. Becker, the Trotter family's doctor, to clarify the results. Del at first refuses, but after more taunting from Reg he changes his mind. Reg, meanwhile, is clearly outstaying his welcome at the flat, having spent all of Rodney and Grandad's money, drunk all their beer, and written a bet on one of Rodney's GCE certificates.
After visiting Dr. Becker, Del reveals that his blood type is actually not different and that Reg had altered them in an attempt to isolate Del and take his place in Nelson Mandela House. Furthermore, he has found out that Reg was actually a porter at the Newcastle hospital, not a patient, and is on the run after stealing numerous items from the hospital. Defeated, Reg leaves. The others are glad to see him go, although Del still gives him some money on his way out. The episode ends with Del hugging Rodney and Grandad.
Tropes:
- Casting Gag: John Sullivan said he cast Peter Woodthorpe as Reg because of his resemblance to David Jason, although the latter always claimed that he couldn't see the likeness.
- Christmas Episode: The last one until 1993's "Fatal Extraction" in which the storyline actually takes place on or around Christmas.
- Foreshadowing: The parentage of one of the Trotter brothers is brought into question. This subject would be raised again in "The Frog's Legacy" (albeit with Rodney rather than Del) and eventually resolved in "Sleepless in Peckham".
- I Am Not Your Father: Reg claims he is not Del's biological father. While Del does not mind this, as he could never stand the man, it causes a schism in the family as he is excluded from a reunited Grandad and Rodney with Reg. Turns out, though, Reg was lying about this and had doctored the medical papers.
- Jerkass: Reg Trotter, who just packed his bags and left his family to fend for themselves after his wife Joan died. 18 years later, he has not improved.
- Knight of Cerebus: While Reg has his humerous moments, his solo appearance causes serious tension within the Trotter household.
- Murder the Hypotenuse: Reg essentially attempts a non-lethal case against Del, knowing he is the one Trotter who's wary to him. Reg concocts a scheme that convinces the household that Del was an illegitimate child born from an affair. leaving Del's pride wounded and isolating himself from the others, and Reg to reclaim his place as the Trotter patriarch. Sure enough, Reg is quickly mooching off of Grandad and Rodney in Del's absense.
- My Friends... and Zoidberg: Reg does this a few times when he tries to split Del off from the rest of the family.Reg: [dealing cards] One for me, Dad, Rodney, Kemosabe.
- One-Shot Character: This is the only appearance of Reg Trotter in Only Fools and Horses (he notably did not return for Grandad's funeral), although he would reappear in Rock & Chips.
- Orphaned Punchline: Reg delivers the final line of a funny story:Reg: I saw him years later, and he still had the scar!
- Strong Family Resemblance: Peter Woodthorpe was cast as Reg because of his passing resemblance to David Jason. He even dresses the same way as Del.
