I've had a reply from DEFRA detailing the legal position on ragwort:

"The answers to your questions are as follows:

a) No - it is not illegal to have Common Ragwort growing on land.

b) Under the Weeds Act 1959 the Secretary of State has a discretionary
power to serve a notice on an occupier of land on which Common Ragwort
is growing requiring the occupier to take action to prevent the spread
of weeds. The Act permits authorised persons to enter land to inspect
whether an enforcement notice has been complied with. If an occupier
has unreasonably failed to comply with the notice he or she shall be
guilty of an offence and on conviction liable to a fine. The Act also
has additional powers which enable the Secretary of State to take action
to arrange for the weeds to be cleared and recover the cost of doing so,
if necessary through the Courts.

c) It is not a notifiable weed and there is no requirement to inform
Defra or any other person or body of the presence of ragwort. However
Ragwort is poisonous to livestock and horses, and can have fatal
consequences. Defra therefore investigates complaints about Ragwort
spreading to grazing land, land used for conserved forage and other
agricultural activities.

The Ragwort Control Bill, which would amend the Weeds Act, has completed
its passage through the House of Commons and is due to have its Second
Reading in the House of Lords on 17 October. A central part of the Bill
is a Code of Practice to Prevent and Control the Spread of Ragwort. You
can see a copy of the draft Code by clicking on

http://www.defra.gov.uk/corporate/co...tcop/index.htm

We will be inviting formal comments on the draft Code if the Bill is
adopted, but any comments received in the meantime will be taken fully
into account in drawing up the final text. If the Bill is not adopted,
Alun Michael has given a commitment that he will issue the Code on a
voluntary basis."

--
Kay Easton

Edward's earthworm page:
http://www.scarboro.demon.co.uk/edward/index.htm