| BURTON, Jonathan David ACTIVE | Secretary | 17 Jan 2013 | | | | Robert Bosch Uk Holdings Ltd, Broadwater Park, North Orbital Road, Denham, Uxbridge, UB9 5HJ, Gb-Gbr |
| FROEHLICH, Klaus Bernd ACTIVE | Director | 04 Dec 2024 | | Switzerland | November 1978 | Sia Abrasives (Gb) Ltd, Ellistones Lane, Greetland, Halifax, West Yorkshire, HX4 8NH |
| KIRN, Julia Viktoria ACTIVE | Director | 01 Jun 2026 | | Switzerland | September 1986 | Sia Abrasives (Gb) Ltd, Ellistones Lane, Greetland, Halifax, West Yorkshire, HX4 8NH |
| BOWYER, Peter James RESIGNED | Secretary | | 07 May 2001 | | | Appynest School Road, Risby, Bury St Edmunds, Suffolk, IP28 6RG |
| COBHAM, John Graham RESIGNED | Secretary | 19 Jan 2004 | 17 Jan 2013 | | | Sia Abrasives (Gb) Ltd, Ellistones Lane, Greetland, Halifax, West Yorkshire, HX4 8NH |
| DAVIDSON, Alan Lloyd RESIGNED | Secretary | 26 Jun 2001 | 09 Jan 2004 | | | 8 Abbey Court, Hade Edge, Holmfirth, West Yorkshire, HD9 2TG |
| ROBSON, James, Mr. RESIGNED | Secretary | 07 May 2001 | 26 Jun 2001 | | | 3 Elsworth Close, Saint Ives, Huntingdon, Cambridgeshire, PE27 5YB |
| BELL, Michael Peter RESIGNED | Director | | 15 Aug 2002 | | March 1944 | Ashley Court, 8 Selwyn Gardens, Newmarket, Suffolk, CB8 |
| BOWYER, Peter James RESIGNED | Director | | 07 May 2001 | | February 1950 | Appynest School Road, Risby, Bury St Edmunds, Suffolk, IP28 6RG |
| CASTLE, Andrew Ralph RESIGNED | Director | 17 Jan 2013 | 01 Apr 2015 | United Kingdom | August 1957 | Robert Bosch Uk Holdings Ltd, Broadwater Park, North Orbital Road, Denham, Uxbridge, UB9 5HJ, Gb-Gbr |
| EBERLE, Roland Marcel RESIGNED | Director | 14 Feb 2007 | 22 Oct 2012 | Switzerland | December 1953 | Haustrasse 17, 8570 Weinfelden, Switzerland |
| ELEUTHERI, Roger RESIGNED | Director | 01 May 2009 | 22 Oct 2012 | Switzerland | May 1975 | 3 Santorini, City Island, Leeds, West Yorkshire, LS12 1DP |
| HEESE, Marcel RESIGNED | Director | 30 Aug 2024 | 01 Jun 2026 | Switzerland | July 1978 | Sia Abrasives (Gb) Ltd, Ellistones Lane, Greetland, Halifax, West Yorkshire, HX4 8NH |
| HOFFMANN, Steffen Tobias, Dr RESIGNED | Director | 31 Mar 2015 | 01 Dec 2020 | England | November 1965 | Broadwater Park, North Orbital Road, Denham, Uxbridge, Middlesex, UB9 5HJ, England |
| KELLER, Stephan Dieter RESIGNED | Director | 22 Oct 2012 | 17 Jan 2013 | Switzerland | April 1969 | Muhlewiesenstrasse 20, Ch8501, Frauenfeld, Switzerland, Switzerland |
| LEPPLE, Ute Tanja RESIGNED | Director | 22 Oct 2012 | 21 Jun 2024 | Switzerland | February 1965 | Luterbachstrasse 10, Luterbachstrasse 10, 4528 Zuchwil, Switzerland, Switzerland |
| LUTHI, Robert RESIGNED | Director | 25 Feb 1992 | 31 Dec 2000 | | December 1952 | Speicherstr 34a, Frauenfeld 8500, FOREIGN, Switzerland |
| MAHRLE, Gerhard RESIGNED | Director | 26 Feb 2001 | 31 Mar 2009 | | April 1957 | Saentisstrasse 29, 9030 Abtwil, Switzerland |
| MENELL, Anthony John RESIGNED | Director | | 31 Dec 1998 | | August 1937 | Walnut Tree Cottage, Littlebury Green, Saffron Walden, Essex, CB11 4XB |
| MEYER, Anthony Guy Lawrence RESIGNED | Director | | 31 Dec 2000 | | September 1944 | The Maltings 53 St Peters Street, Duxford, Cambridge, Cambridgeshire, CB2 4RP |
| PROFT, Manfred RESIGNED | Director | 26 Jun 2001 | 14 Feb 2007 | | October 1949 | 5 Lowana Crescent, Forest Hill, Victoria 3131, Australia |
| RAJAKOBA, Vonjy Rakotonaivo RESIGNED | Director | 01 Dec 2020 | 31 Aug 2024 | England | February 1971 | Sia Abrasives (Gb) Ltd, Ellistones Lane, Greetland, Halifax, West Yorkshire, HX4 8NH |
| ROBSON, James, Mr. RESIGNED | Director | | 31 Dec 2002 | United Kingdom | November 1947 | 3 Elsworth Close, Saint Ives, Huntingdon, Cambridgeshire, PE27 5YB |
| SCHIFFERLE, Peter Alfons RESIGNED | Director | 25 Feb 1992 | 14 Feb 2007 | | March 1944 | Burgstrasse 43, Weinfelden, 8570, Switzerland |
| SERRE, Marianne RESIGNED | Director | 01 May 2017 | 16 Sep 2020 | England | September 1964 | Sia Abrasives (Gb) Ltd, Ellistones Lane, Greetland, Halifax, West Yorkshire, HX4 8NH |
| STAHELI, Beat Adolf RESIGNED | Director | 01 May 2009 | 22 Oct 2012 | Switzerland | January 1956 | Speicherstrasse Ss.8500, Frauenfeld, Switzerland |
| TIMMINS, Ian Michael RESIGNED | Director | 22 Oct 2012 | 01 May 2017 | United Kingdom | September 1966 | Sia Abrasives (Gb) Ltd, Ellistones Lane, Greetland, Halifax, West Yorkshire, HX4 8NH |
| ZWICKY, Dario Willy RESIGNED | Director | | 25 Feb 1992 | | August 1930 | Holdenstrasse 9, 8500 Framenfeld, FOREIGN, Switzerland |
| ZWICKY, Frank RESIGNED | Director | | 25 Feb 1992 | | May 1955 | 1m Lehen, Fruthwilen, FOREIGN, Switzerland |