GPMU regional officer Tom Lowe said 150 employees at the Kidderminster printers were made redundant, without any formal paperwork being issued.
The company had taken the decision to proceed with the closure and redundancies, following talks with TPL's owners, Singaporean media group Times Publishing, and GPMU officials last week.
Lowe said delays in the paperwork for those being made redundant, were due to Singaporean management wanting to see all the figures before proceeding.
"It's a disgrace the way the workforce is being treated," he said.
TPL announced it was to close its Kidderminster plant last month (PrintWeek, 11 March), a decision that was announced to its workforce by GPMU officials.
The GPMU is still investigating taking legal action against TPL, for what it termed as a breach of its 90-day consultation process.
The Goodhead Group's web division benhamgoodheadprint (bgp) emerged as the biggest beneficiary of TPL's demise (PrintWeek, 8 April).
It picked up 28 titles previously produced by TPL, which it will print at bgp's Bicester site.
Of those 17 were for Future Publishing and 11 from IPC.
Future moved another nine of its titles from TPL to William Gibbons in Wolverhampton (PrintWeek, 18 March).
Other publishers with titles at the site included Reed Business Information (RBI) and Haymarket.
RBI re-assigned its 10 titles with TPL to Polestar Colchester and Wyndeham Heron (PrintWeek, 11 March).
Outcry as TPL lays off 150 employees
TPL made two-thirds of its workforce redundant on 8 April, a decision that GPMU officials have branded as appalling.