[2] Under the Duke of Newcastle, British foreign policy was to isolate France by bringing Spain into the Pragmatic Alliance that fought the war; he ordered his diplomats in Madrid and Vienna to do all they could to support a rapprochement between the two countries.

The influential British Ambassador to Spain, Sir Benjamin Keene, suggested this could only be achieved by including Sardinia and Britain, but Spanish foreign minister José de Carvajal y Lancáster felt it was too great an expansion.

While he eventually agreed to send Count St Marsan to Madrid, he refused to hold direct talks with Austria, which meant much of the negotiating was done by Carvajal, supported by Keene.

[5] While in principle the terms were relatively straightforward, negotiations were delayed by arguments over protocol; to demonstrate equality between the parties, St Marsan insisted he be allowed to sign one of the three copies first, which was rejected by both Spain and Austria.

[6] A further delay occurred when Esterhazy fell ill and had to be replaced by Count Migazzi; on 10 April, Austria and Spain signed a draft treaty and only Keene's determination ensured discussions on adding Sardinia continued.