Adam Otterburn was an important servant of the Scottish monarchy as a lawyer and a diplomat. Early in his career, in May 1525 the English ambassador Dr Thomas Magnus recommended him to Cardinal Wolsey for an annual pension of £20. When James V assumed the throne as an adult ruler and rejected the Douglases and their associates, Otterburn drew up charges of treason against them on 13 July 1529. On 8 November 1529 he was one of the Scottish commissioners who met English diplomats at Berwick-upon-Tweed. This meeting discussed the possible restoration of the Earl of Angus, an issue which Henry VIII could use as leverage to decide James's choice of future bride. A five-year truce was concluded and the Douglases were to go into English exile.
In May 1532 he was of the first 15 lawyers appointed as Senators of Justice. While in England he was knighted by James V (in his absence) as Sir Adam Otterburn of Redhall on 16 February 1534. Redhall, his other estate, is within Edinburgh near Longstone.
Adam Otterburn signed a border peace treaty in London on 11 May 1534. After the English Reformation, in 1536, Henry VIII requested a meeting with James V, and Otterburn was sent to London again to discuss Henry's motives and the possible agenda. He was in London during the arrest and conviction of Ann Boleyn. In April 1537 Otterburn and other courtiers joked with the English messenger Henry Ray about English Friars who were now refugees in Scotland.
In June 1538 he wrote a speech in French to welcome Mary of Guise to Edinburgh. In August 1538 he was imprisoned in Dumbarton Castle and next year deprived of office and fined £1000 for communicating with the forfeited Earl of Angus. After the death of James V, Otterburn received a gift of crossbows and armour.
The English diplomat Ralph Sadler reported that Otterburn was a member of Cardinal Beaton's pro-French faction, but Adam insisted the contrary, attributing his troubles and difficulties during the adult rule of James V to his pro-English position. The Governor of Scotland, Regent Arran, ordered Otterburn's arrest on 28 April 1544 but Robert Reid the Bishop of Orkney interceded for him.
"Our people do not like of it. And though the governor and some of the nobility have consented to it, yet I know that few or none of them do like of it; and our common people do utterly mislike of it. I pray you give me leave to ask you a question: if your lad was a lass, and our lass were a lad, would you then be so earnest in this matter? ... And lykewise I assure you that our nation will never agree to have an Englishman king of Scotland. And though the whole nobility of the realm would consent, yet our common people, and the stones in the street would rise and rebel against it"
When the English army intent on the destruction of Edinburgh landed at Granton and took Leith, as Provost of Edinburgh, Adam Otterburn was sent out with two heralds to parley with the Earl of Hertford on the morning of 5 May 1544. Hertford had been instructed not to negotiate, so Adam replied in defiance and refused to yield up the town. Hertford had not yet landed his guns so offered to wait till 7:00 pm.
During an interlude in the war with England, Otterburn was concerned to recover money owing to him. His holding of lands at Auldhame, like those of his neighbours Oliver Sinclair, the favourite of James V, and John, 5th Lord Borthwick, required duties to be paid to Cardinal Beaton. Adam wrote to the Cardinal hoping for money owed to him by Sinclair, and he noted that Borthwick and other landowners south of the River Forth sold their wool in England. Adam was now distrusted by Regent Arran and briefly imprisoned with a threat of further lawsuits. Friends like Elizabeth Gordon, wife of John Stewart, 4th Earl of Atholl wrote to Mary of Guise on his behalf. They were closely allied; Adam's son John had married the Countess' sister in law, Janet Stewart.
In October 1546, Adam set out with David Panter and a servant of d'Oysel, the French ambassador in Scotland to meet with Henry VIII at Oatlands. They brought the Scottish ratification of the Treaty of Ardres or Camp. Before they left Adam complained he had not enough money and horses to get to Musselburgh (a town close to Edinburgh). While they were waiting to see Henry the other diplomats were delighted to see them arguing. In March 1547, three of his servants were allowed to return to Scotland.
Otterburn was still negotiating for peace in London before the Battle of Pinkie. On Sunday 7 August 1547 he went to Hampton Court and met Edward VI of England. There he was dismissed as a diplomat by the council as it was now a time of hostility. He was given £75 as a gift for his departure. Otterburn saw,
"afoir my eis verray gret preparatioun of weir, and actualie the gret hors, the harnes, the hagbutaris, and all gorgious reparrale set forwart towart our realme."
Before my eyes very great preparation of war, and actually the great horse, the armour, the firearms, and all the gorgeous equipment set forward towards our realm.
The "gorgeous" equipment included leather horse armour designed and made by the workshop of the Italian artist Nicholas Bellin of Modena. On Monday he returned to Hampton Court and had further discussions with the Protector Somerset. He wrote to Regent Arran urging him take his warnings of the English invasion seriously, and begged him to allow George Douglas of Pittendreich to negotiate with Somerset, writing; "I dreid ye will nocht gif credence quhill ye se thame cum in at the dur," (I dread you will not believe till you see them come in the door). Arran had already set up a system of coastal watchers and warning beacons. However, his army was defeated by the English at the battle of Pinkie on 10 September 1547.
In his letters in 1546 and 1547 Otterburn mentions that he was "aged and sickly", but Otterburn died after an assault in Edinburgh by a servant of Regent Arran on 3 July 1548, "sore hurt on the head and his servant slain at his heels." Patrick Mure, laird of Annestoun near Lanark, and his son were charged with treason for his murder, their last recorded summons for the crime was at the instance of Mary of Guise.
Adam married firstly, Janet Rhynd, and secondly, Euphame Mowbray, with whom he had three sons, John, Robert and Thomas. He had three daughters, Margaret, Janet, and another whose name is unknown. His eldest daughter Margaret married Sir John Wemyss of Wemyss. In February 1544 another daughter was married and Adam asked Mary of Guise for financial support as 'sik materis requiris coist and expensis', and again in 1546 he mentioned to David Beaton his difficulty in paying 'my dochteris tocher.' His son John married Janet Stewart, sister of the Earl of Atholl.