oh - love the Thomas Chatterton icon
( that wondrous boy - Horace Walpole who shafted him )
no it is not illegal it is a potentially exempt transfer
and ceased to be a PET after seven years
remember on your death you can transfer £325k ( or whatever it is on your death ) free and the £20k will count against that
try googling Potentially exempt transfer
and there is the govt handbook here
http://www.hmrc.gov.uk/manuals/ihtmanual/ihtm04057.htm
have hours of innocent fun
Remember rules on serial giving
if you give 20k and then 30 k two years later it is counted as 50k and the clock starts again ( at the 30k point )