Article 51U.K.
1.When a person in receipt of benefits, in particular:
(a)invalidity benefits;
(b)old-age benefits awarded in the event of unfitness for work;
(c)old-age benefits awarded to elderly unemployed persons;
(d)old-age benefits awarded in the event of cessation of a professional or trade activity;
(e)survivors' benefits awarded in the event of invalidity or unfitness for work;
(f)benefits awarded on condition that the means of the recipient do not exceed a prescribed limit,
is staying or residing in the territory of a Member State other than the State in which the institution responsible for payment is situated, administrative checks and medical examinations shall be carried out, at the request of that institution, by the institution of the place of stay or residence of the recipient in accordance with the procedures laid down by the legislation administered by the latter institution. The institution responsible for payment shall, however, reserve the right to have the recipient examined by a doctor of its own choice.
2.If it is established that the recipient referred to in paragraph 1 is employed or self-employed or has means in excess of the prescribed limit while receiving benefits, the institution of the place of stay or residence shall send a report to the institution responsible for payment which has requested the check or examination. This report shall indicate in particular the nature of the employment or self-employment pursued by the person concerned, the amount of earnings or means which he has had during the last complete quarter, the normal earnings obtained in the same area by an employed person or a self-employed person at the same level as the person concerned in the occupation which he followed before becoming an invalid over a reference period to be determined by the institution responsible for payment and, where appropriate, the opinion of a medical expert on the state of health of the person concerned.