Previously, Slaughters was sole principal legal adviser to UK-based chemical company Laporte, one of the largest international life science specialist chemical manufacturers in Europe.
But Laporte chose A&O as second principal adviser after Slaughters was conflicted out of the sale of one of the company's properties.
Richard Cranfield, A&O's head of corporate, says: “They are happy with the job we have done for them. The message is they liked the service they got compared to what they are used to getting.”
Cranfield also suspects the company will start operating a panel.
A&O's first deal for Laporte is the £20m sale of a chemicals site at Four Ashes, Wolverhampton to Schenectady Europe.
The deal is still subject to regulatory clearance from officials in Germany.
Jim Leng, chief executive of Laporte, says: “We will use A&O again. This is the first thing they have done for us, but we have got to know A&O over a period of time and we are pleased we have got them on board.”
Slaughters says it was conflicted out of the Four Ashes transaction because the property was originally sold to Laporte by another Slaughters client.
A Slaughters spokesman adds: “We have been working on other Laporte deals.”
Laporte does not have a formal panel, but it does prioritise its advisers.
Leng says: “A&O and Slaughters are our two principal firms.”