Are Electronic Signatures legal in UK?

[TheCyclingProgrammer]

I'm interested to understand the security behind this a bit better but a quick google didn't get me much further than Adobe's own marketing spin.

I vaguely understand how GnuPG signing works. Is it anything like that?

How do you authenticate a signed PDF? What trust does it place in 3rd party "authorities"?

Are there compatible free software solutions based on an open-standard?

Some interesting info in the FAQ for the service I use:
https://rightsignature.com/faq#safer
https://rightsignature.com/faq#otherparty

Email receipts and IP tracking go some way towards identity verification.

The only 100% bullet proof way of confirming somebody's identity is by meeting them in person. I'd say that electronic signatures offer a level of verification beyond that of a regular signature that has been obtained via post/fax/scanned email etc.

It also offers safeguards against things like documents being altered after they have been signed as they signed keys that change if you change the document.

The PDF you download from RightSignature of a signed document contains the certificate/verification data.