I think the fact that it happened in a shop and that there was cc tv footage that helped convict her suggests that she saw who dropped it and knew who it belonged to
NC for this as friends and family would be able to identify me.
I rang the police 6 weeks ago to report my phone stolen, I believed at a pelican crossing. To my surprise they took it really seriously, asked for my description, the time it happened and said they'd check CCTV.
They rang back a couple of weeks later to say they'd checked the CCTV and my phone had fallen out of my bag or pocket. I started to apologise for wasting their time but the WPC stopped me and said that a young man standing behind me had noticed, picked up my phone, looked around to see if I or anyone else noticed, then quickly walked off in the other direction. She said it was considered opportunistic theft and if they can identify him by putting his picture in the local paper, then they will prosecute.
I know a phone has more value than £20 (usually), but the police said to me that this man could have tapped me on the shoulder, he could have asked the people waiting to cross "Does this belong to anyone?" Or failing all that, he could have handed it in at the police station up the road. Instead he switched it off and walked away. He made a choice to take it having seen where it came from, which legally speaking, shows intent. They said this would be the case whether I dropped my phone, wallet, keys, money or something of monetary value.
I feel daft for not securing it, but in the same situation I would have got the person's attention and handed it back, not said "Ooh finders keepers!"
If this woman has been caught essentially doing the same thing (and has form), I say good. She's committed a crime. £20 is a decent amount of money and half my weekly food budget.