Spain's leading bank, Santander, has this past month made a €1.6bn, all paper, bid for UK bank Alliance & Leicester (A&L). The one-for-three share offer came as a relief for the UK's seventh-largest bank, which had begun to face increasing liquidity issues and defaults in its mortgage book, say lawyers close to the deal.

Santander had originally entered into takeover negotiations with A&L last summer but broke off talks when an agreed offer value could not be reached. Santander has walked away from a bid target before. It did exactly the same when it acquired Abbey National, the UK's second-largest mortgage lender, in 2004.

For the latest UK deal, Santander has again turned to Uría Menéndez's best friend Slaughter and May, which previously advised the bank on last year's historic combined €71bn acquisition of ABN Amro – alongside Royal Bank of Scotland and Fortis. Uría Menéndez is providing domestic advice through partner Salvador Sánchez-Terán. US firm Davis Polk & Wardwell also has a corporate role while A&L has turned to Allen & Overy, with Spanish support coming from Carlos Albiñana and Juan Barona.

In the 2004 acquisition by Santander of Abbey, Slaughter and May acted for long-time client Abbey, leaving Clifford Chance and Pérez-Llorca to act for Santander.

Santander's strong position, lawyers say, is due to its negligible exposure to the sub-prime crisis, in part forced by the Bank of Spain's refusal to allow off-balance sheet structures. With its impressive acquisition and then €9bn sale of Italy's Banca Antonveneta, as part of the division of ABN Amro, and the €4bn it has just received from the sale and lease back of its property portfolio, the current sixth-largest global bank by capitalisation has financial muscle that competitors can only admire, say some.

To finance further acquisitions it is reportedly now contemplating selling off its fund management unit, which could realise €2.5bn. Such a move could attract interest from a number of international investment banks looking to expand their presence in South America or to gain a foothold in Spain.

The bank is also in discussions to divest its €4bn insurance division, with interest reportedly from UK's Aviva, Italy's Generali, Germany's Allianz, France's AXA and Switzerland's Zurich.

Spanish group Mapfre could also enter the bidding but, say lawyers, could face more difficulties with the competition authorities than the others. Allianz may be in the best position, suggest some, as it could offer in exchange its Dresdner retail banking business – Santander has already announced its desire to expand into Germany.

With Santander maintaining its growth strategy, Spain's leading law firms are unsurprisingly applying maximum client relationship efforts towards the bank.

Santander has no formal legal panel but its in-house lawyers, led by Juan Guitard, have placed the work they cannot handle among most of the top tier domestic M&A heavyweights.

Recently, Salvador Sánchez-Teran was in action for Santander again, advising their Private Equity group on the €722m acquisition of a 49% stake in Invinsl, which is the owner of a 48% stake in Autopista Central and a 50% stake in Rutas del Pacífico (Chilean toll road concessions). The remaining 51% of Invinsl was acquired by Spanish constructors Abertis.