in fact here are all three IR examples which are quite helpful and the link !
 
Example 1
Father gifts property worth £200,000 to his son for no monetary consideration. There is no mortgage on the property therefore no chargeable consideration is passing.  
 
The transfer in this instance is not notifiable and may be self-certified with form SDLT60.
 
Example 2
Mother gifts property worth £200,000 to her daughter for no monetary consideration. There is however a mortgage on the property of £150,000 at the date of the transaction.  
 
Stamp Duty Land Tax is therefore due at the rate of 1% on this outstanding mortgage sum. This transaction is notifiable on form SDLT1.
 
Example 3
Husband wishes to transfer half of his property worth £300,000 into his wife’s name. No cash changes hands but the property is subject to a mortgage for £200,000.  
 
As half of the property is being transferred, half of the mortgage debt is being taken over by the wife.  
 
There is no Stamp Duty Land Tax due on this £100,000 chargeable consideration as it does not exceed the £120,000 threshold but the transaction is still notifiable.  
 
http://www.hmrc.gov.uk/manuals/sdltmanual/SDLTM00330a.htm