Twenty-nine years is a long time in anyone's language, but in soap opera terms, it's literally hundreds of lifetimes. Keeping up with who's related to who and how on Channel Ten's Neighbours, Australia's longest-running soap, is as important as making sure that Susan Kennedy's dangly earrings match from one take to the next. When slip-ups happen - and they do, despite an extensive in-house database, and meticulous archives on fansites, where character biographies can run into the tens of thousands of words - it doesn't go unnoticed by the legions of the show's fans, many of whom have been faithfully tuning in since day one.
For Jack Seymour, a 22-year-old British fan from Lincolnshire, historical inconsistencies in Neighbours are common.
He can reel off clangers that have roots stretching back to his own childhood.
''Characters' ages and birthdays often change a lot,'' Seymour says. ''Kate celebrated her 18th birthday in early March, but her 22nd was in late April four years later. In 2007, Susan and Karl were talking about Libby and mentioned that she was 27, however Libby celebrated her 21st in 1998. Holly, Karl and Izzy's love child arrived in 2013 as an eight-year-old, but she was actually born in 2007, when Susan and Karl remarried in London and Izzy went into labour on a boat on the Thames. And when Lauren returned with three teen children in 2013, not only was she told she was highly unlikely to have children in 1993, Mason, her oldest, was supposedly born in 1999. However, in 2013 he was an 18-year-old.''
Producer Jason Herbison got his first job out of high school in the Neighbours writing room, went on to write for Seven's Home and Away, which is just two years younger than Neighbours, and returned to Neighbours as series producer for Fremantle Media in 2012. He says plot inconsistency is an occupational hazard with the sheer number of episodes produced (240 a year) and the turnover of actors and writers. Generally, he says, fans are forgiving, and there are some inaccuracies that are more acceptable than others.
''We do take dramatic licence,'' Herbison explains. ''The term, 'retcon' [retroactive continuity], refers to when you bring back past characters or evoke a previous situation but change it a little bit because it now sits better in the current storytelling. The best example of that is when you recast, which happens most commonly with young actors.''
According to an Australian drama producer who wishes to remain anonymous, the continuity people ''just don't exist'' as they once did.
''The people who started these shows have all either moved on, are out of the business or are dead,'' the producer said. ''So the job of watching those details is now usually the responsibility of the story editor or story producer, and to be honest, they can often rely on the actors who have been there longer than them.''
Which works only when there are actors around who have that memory. In shows where they don't, it can lead to some interesting moments, most notably in American soaps, where the cast and crew can change frequently.
The Young and The Restless' Cane Ashby has been (at various stages in the series) a long-lost son switched at birth, an orphan who used identity theft to lie his way into the series' main family, and the son of an Australian criminal hiding out. On Days of Our Lives, in 1992, when characters John Black and Isabella Toscano married, their son Shawn (aged about four) was the ring-bearer and shortly after the ceremony, Isabella gave birth to their son Brady. Those children were recast in 1999, however, and Brady is now noticeably older than his brother.
Even The Flintstones has been tripped up by continuity, with Wilma given two completely different maiden names - ''Pebble'' and ''Slaghoople'' - simply because the writers forgot they had already named her.
Herbison can't recall anything quite as glaring on Neighbours or Home and Away.
''There certainly have been a few moments where I haven't remembered something or I've read something a fan has said and gone, 'Ooh, I'd forgotten about that!', but nothing too spectacular,'' he says.
Of course the nature of the genre means that plot developments routinely test audiences' suspension of disbelief. Herbison's favourite is Harold Bishop's resurrection in the 1990s, when, after going missing at sea, he turned up a few years later with amnesia, having been taken in by the Tasmanian wing of the Salvation Army.
''That was an incredibly successful storyline,'' says Herbison. ''It was one that you can only do once a decade. There's another very famous character from the past, Dee Bliss, played by Madeleine West, who also disappeared at sea, and every year I get asked, 'Are we going to bring Dee back from the dead?' And my response is, 'For one, I don't know if the actress would, but number two, we'd have to find a different way of doing it than we did with Harold, and we haven't come up with it yet.''
For Jack Seymour, keeping up with the plot is all part of the fun.
''Although [inconsistencies] suspend reality, at times they manage to pull it off and get away with it. I have to admit I had difficulty believing Brad and Lauren's backstories to begin with. Doug told us in 2005, when he returned for the 20th-anniversary episodes, that Brad and Beth were still happily married. However, last year, Brad returned [swapping heads as a new actor took over the role] with two teen children by new wife Terese, who he's supposedly been married to for almost 20 years. However, I still love the show and won't ever miss an episode.''