The Queen did the last State Opening of Parliament, after the December Election, without regalia because it was an extra opening that had to be squeezed into her schedule.
The State opening normally happens in the fall. And IIRC, they just had one last fall. before the Election was called. So to save prep time, a stripped down opening was held, she did not wear a gown, and took a Rolls Royce instead of a carriage to Parliament. The Imperial State Crown was on a pillow. (Like what she does for Scottish Parliament openings, because in that case, the Scottish regalia is very fragile and wearing it would damage it.)
The crown weighs a ton for a ninety something year neck.