Then came the next bombshell as it emerged that Reform MS for Pen-y-bont Bro Morgannwg Sarah Cooper-Lesadd was defecting to Plaid Cymru.
Reform only found out about it after BBC Wales asked the party for a response to the story.
Moments earlier she had been sitting on the Reform benches and had been due to speak for the party in the chamber.
Most of Plaid Cymru’s MSs – including some government ministers – were only told about the defection plan at their group meeting earlier in the day.
The defection needed the group’s approval and some Plaid MSs wanted assurances that Cooper-Lesadd fully understood what it meant to be a Plaid Cymru member.
The defection was approved with the necessary two thirds majority. But it wasn’t backed by everyone.
At a hastily arranged news conference in the Senedd, Cooper-Lesadd said her switch to Plaid followed “a period of reflection and deliberation” and that she had found “the right political home”.
The move was completely unconnected to Dan Thomas’s arrest.
Neither Cooper-Lesadd nor Plaid will say how or when the talks over the defection began, only that the process had gone on for “a while” and she had been on a “journey”.
The defection, just four months on from May’s Senedd election, has raised fresh questions about the electoral process where voters were required to back a party rather than an individual.
Jess Blair, from the Electoral Reform Society, said that while defections were “nothing new” there was more of an “accountability gap” given the Welsh voting system.
“When this electoral system was put in place a review mechanism was also built into that process and what we need now is to really see that review take place,” she said.
By Wednesday, Reform’s focus was on appointing a new leader.
A party official from London came to explain the process to MSs, and Dan Thomas was also at that meeting.
As is the case when a new leader is needed, various names were being discussed.
James Evans was seen as one obvious contender.
When it was announced that he would make a media statement reporters scrambled to hear what he had to say.
“Having consulted with my family…I will not be putting my name forward,” he said, despite “a majority” of the party’s MSs backing him to take over.
By Thursday morning it was looking increasingly likely that Helen Jenner would be the next leader.
While Reform UK bosses in London have not had any formal input to the process, sources say there have been “signals” that Jenner – a Farage ally since the UKIP days – would be seen as a good choice in HQ.
Confirmation of Jenner’s appointment is expected as soon as Monday.
“I feel we’re more united than ever,” said Llŷr Powell.
“For us it’s a new start next week and that’s what we’re building on.”
Politics Wales is on BBC1 Wales at 10:00 BST on Sunday 20 September and iPlayer.
