Definition: Births, Deaths, and Marriages Registration Act 1995 No 16 S.2 (interpretation):
“Still-born child” means a dead foetus that—
(a) Weighed 400g or more when it issued from its mother; or
(b) Issued from its mother after the 20th week of pregnancy.

“Dead foetus” means a foetus that, whether or not the umbilical cord had been severed or the placenta had detached, at no time after issuing completely from its mother breathed or showed any other sign of life (such as beating of the heart, pulsation of the umbilical cord, or definite movement of the voluntary muscles).

Cremation Regulations 1973 (SR 1973/154) S. 4: Restrictions on cremation
(6) … the body of a still-born child may be cremated without the permission of the Medical Referee if there is delivered to the crematorium authority either a written certificate or a statutory declaration in accordance with and containing the particulars required by section 46A(a) or (b) of the Burial and Cremation Act 1964.

Burial & Cremation Act 46A: Still-born children
(1) A still-born child must not be buried, cremated, or otherwise disposed of unless the person in charge of the disposal has obtained—
(a) a written certificate relating to the cause of the still-birth signed—
  • (i) by a doctor who was present at the birth or examined the child after birth; or
  • (ii) if no doctor was present at the birth or examined the child after birth, by a midwife; or
(b) a statutory declaration, made by the person or 1 of the persons required under the Births, Deaths, Marriages, and Relationships Registration Act 1995 to notify the birth, to the effect that the child was born dead, and that—
  • (i) no doctor or midwife was present at the birth; or
  • (ii) it is impossible to obtain a certificate under paragraph (a) from a doctor or midwife present at the birth; or
(c) a coroner's authorisation.