Sir Simon Stevens tells the BBC the Covid-19 crisis has shone a "very harsh spotlight" on the sector.
The chancellor is expected to announce plans to recruit 13,500 extra staff at job centres.
Health Secretary Matt Hancock says he is "very worried about employment practices in some factories".
The applause was inspired by the weekly Clap for Carers during the peak of the coronavirus lockdown.
The acting leader of the Liberal Democrats asks whether Nigel Farage has broken quarantine rules.