Question: How was Abbey National expanded,  leading to the forming of Cahoot?

Context paragraphs:
Department of Public Works (South Africa): The Department of Public Works is one of the ministries of the South African government.  It is responsible for providing accommodation and property management services to all the other ministries of the South African government.  It is also responsible for promoting the national Expanded Public Works Programme and for encouraging the transformation of the construction and property industries in South Africa.

Abbey National: Abbey National plc was a bank based in the United Kingdom and former building society, which latterly traded under the Abbey brand name.  As the former Abbey National Building Society, it was the first building society in the United Kingdom to demutualise, doing so in July 1989.  The bank expanded through a number of acquisitions in the 1990s, including James Hay, Scottish Mutual, Scottish Provident and the rail leasing company Porterbrook.  Abbey National launched an online bank, Cahoot, in June 2000.

Cahoot: cahoot is the internet division of Santander UK plc, the British subsidiary of the Santander Group.  Cahoot was launched in June 2000, as the internet-based banking brand of Abbey National plc, and by December 2008, it had 750,000 customers.  Cahoot is based in Belfast, Northern Ireland.

Statue of Sherlock Holmes, London: A statue of Sherlock Holmes by the sculptor John Doubleday stands near the supposed site of 221B Baker Street, the fictional detective's address in London.  Unveiled on 23 September 1999, the sculpture was funded by the Abbey National building society, whose headquarters were on the purported site of the famous address.  As no site was available on Baker Street itself the statue was installed outside Baker Street tube station, on Marylebone Road.  Doubleday had previously produced a statue of Holmes for the town of Meiringen in Switzerland, below the Reichenbach Falls whence the detective fell to his apparent death in the story "The Final Problem".

Holyrood Abbey: Holyrood Abbey is a ruined abbey of the Canons Regular in Edinburgh, Scotland.  The abbey was founded in 1128 by King David I.  During the 15th century, the abbey guesthouse was developed into a royal residence, and after the Scottish Reformation the Palace of Holyroodhouse was expanded further.  The abbey church was used as a parish church until the 17th century, and has been ruined since the 18th century.  The remaining walls of the abbey lie adjacent to the palace, at the eastern end of Edinburgh's Royal Mile.  The site of the abbey is protected as a scheduled monument.

Duiske Abbey: Duiske Abbey National Monument, also known as Graiguenamanagh Abbey, is a 13th-century Cistercian monastery situated in Graiguenamanagh, County Kilkenny in Ireland.

Abbey National Building Society v Cann: George Cann lived with his mother, Daisy, in Island Road, Mitcham in London.  She had contributed to the purchase price of the home, and so George held the house on trust for himself and her, even though it was solely registered in his name.  They moved to a smaller house that cost £4000 more in South Lodge Avenue.  To buy it they used the proceeds of selling the Island Road home and got a mortgage from the Abbey National.  Daisy knew this was necessary.  She did not know that George had also taken another mortgage for £25,000.  Later he could not repay and Abbey National wished to repossess the property.  Daisy, whose new partner was also living there, argued that she had a right to remain in the home, because her equitable proprietary right arose before Abbey National, and this coupled with her actual occupation gave her an overriding interest under LRA 1925 section 70(1)(g) (now LRA 2002 Sch 3).  She had started to move in carpets 35 minutes before the charge was completed.  Abbey National argued that when the house was bought with its loan, her right could not arise before.

Advance (trade union): Advance is a certified, independent trade union affiliated to the TUC representing workers within the bank Santander UK, the UK subsidiary of Santander Group.  The union was formerly known as the Abbey National Group Union (ANGU) before it expanded to include staff of Alliance & Leicester and Bradford & Bingley following their acquisitions by Santander.  Its aims are the supporting and representing its members in all aspects of their employment.

Cater Allen: Cater Allen is a private bank operating in the United Kingdom.  It is a subsidiary of Santander UK.  Tracing its history back to a bank founded in Blackburn in 1816, it was independent for 180 years, before being purchased in 1997 by Abbey National.  Cater Allen Offshore was initially run as a separate enterprise within Abbey, but in 2001 it was merged with Abbey National Offshore.

Loughton Orient F.C.: Loughton Orient F.C. was a football club based in Loughton, Milton Keynes, England.  Founded as Abbey National F.C., they joined the South Midlands League Division One in 1994.  In 2004 they changed their name to "Loughton Orient".  In the 2006–07 season they were members of the Spartan South Midlands League Division Two, but they resigned from the league at the end of that season, and subsequently folded.

Supporting paragraphs: Cahoot Abbey National
Answer: The bank expanded through a number of acquisitions in the 1990s