(19)

(11)

EP 0 537 235 A1

(12)

(43) Date of publication: 21.04.1993 Bulletin 1993/16 (21) Application number: 91912356.0 (22) Date of filing: 03.07.1991

(51) International Patent Classification (IPC):  E01F 13/ 08( . ) (86) International application number: PCT/GB1991/001087 (87) International publication number: WO 1992/001116 (23.01.1992 Gazette 1992/03)

(84) Designated Contracting States: AT BE CH DE DK ES FR IT LI NL SE (30) Priority: 04.07.1990 GB 19900014804 08.10.1990 GB 19900021840 (71) Applicant: OVINGTON, Stanley Cottenham CB4 4QU (GB)	(72) Inventor: OVINGTON, Stanley Cottenham CB4 4QU (GB) (74) Representative: Nash, Keith Wilfrid, et al  Pearl Assurance House 90-92 Regent Street Cambridge CB2 1DP Cambridge CB2 1DP (GB)