"one pashmina short of a wardrobe".What's it?

[on the way]

When I was watching a British TV series Miranda,I came across an expression stated in the title.The context is that Miranda and her mother are in a psychiatrist's office for the assessment of Miranda as asked by the police.Miranda's mother explains to the psychiatrist why they are here and therefore the assessment of Miranda is totally unnecessary.In her explaining she says "But to stop Miranda being arrested and charged,I said she was one pashmina short of a wardrobe."
Any help in enlightening me on the meaning of this expression will be much appreciated.

 

[BobK]

Mentally wanting/limited; Miranda's mother explained to the psychiatrist that she had told police that Miranda was not responsible for her actions. There are lots of these 'one X short of a Y' expressions; they have been discussed here several times. One of the more common ones is 'One sandwich short of a picnic'; a search for this might take you to several others.

Miranda Hart (who writes the series) was simply aiming at a new variation on a well-worn theme. In this context 'pashmina' is an article of clothing and 'wardrobe' is used in the abstract sense of 'a complete set of garments'.

b