Lord Rennard has been seen sitting in the chamber for what is thought to be the first time since he was suspended by the Liberal Democrats.
The party's former chief executive sat on the back row of the Lib Dem benches alongside Baroness Tonge, who was forced out of the party over comments she made about Israel.
Lord Rennard was suspended on January 20 pending an investigation into whether he had brought the party into disrepute by failing to apologise to women who made complaints against him.
A QC's inquiry into the allegations concluded that the women's claims were credible but there was insufficient evidence to bring disciplinary charges, and suggested that the peer should apologise to them.
On the day the suspension was announced, Lord Rennard was widely expected to take his seat in the Lords in what would have been interpreted as defiance of the wishes of his party leader Nick Clegg, who has insisted he must apologise before he can regain the whip.
But he failed to turn up after issuing a statement citing ill-health and threatening to take legal action against the party.
While Lord Rennard is suspended by the party, there is nothing to stop him sitting or speaking in the Lords and claiming the £300 daily allowance all peers are entitled to.
By sitting at the back of the Lib Dem block in the Upper House, Lord Rennard has followed the precedent of most peers kicked out by their parties, including expenses cheats such as Lord Taylor of Warwick and Baroness Uddin, who continue to sit on the same benches as their former colleagues.