Article 21 The guarantor

The guarantor shall have his officially registered residence or an establishment in the F1United Kingdom and F2... be approved by the competent authority F3.... The guarantor shall be bound by a written guarantee.

The written guarantee shall state at least:

1. (a)

   the obligation or, in the case of a block security, the type(s) of obligation against whose fulfilment it guarantees the payment of a sum of money;

2. (b)

   the maximum liability to pay that the guarantor accepts;

3. (c)

   that the guarantor undertakes jointly and severally with the party responsible for meeting the obligation to pay, within 30 days upon demand by the competent authority, any sum, within the limit of the guarantee, due once a security is declared forfeit.

Where a written block security has already been given, the competent authority shall determine the procedure to be followed by which all or part of the block security shall be allocated to a particular obligation.