Sadler was sent into Scotland to several times.
In 1540 he tried to embarrass and undermine the authority of Cardinal Beaton, an ally of France, with letters captured from his messenger Alexander Crichton of Brunstane whose ship had been forced by a storm to put into England.
However, James V of Scotland refused to accept that the letters were compromising, and argued in favour of the Cardinal that he had a separate spiritual authority in Scotland apart from the King's own temporal powers.
Later, when the Cardinal was present, James and Sadler compared the captured letters with Beaton's copies, and found a discrepancy.
James V said he was thankful to Sadler and his uncle Henry VIII but still would not find fault in the Cardinal's actions.

Following the Battle of Solway Moss, Sadler was sent to Scotland again, in March 1543, to arrange a marriage between the infant Mary, Queen of Scots, and Edward, Prince of Wales.
He was a successful negotiator for the Treaty of Greenwich, although the marriage was not concluded.
On 22 March 1543 he rode from Edinburgh to Linlithgow Palace to see the queen for the first time.
Mary of Guise showed him the queen out of her swaddling and Sadler wrote that the infant was "as goodly a child I have seen, and like to live".
Mary reminded him that in turn Regent Arran wanted his son James Hamilton to marry Princess Elizabeth.
Mary tried to work on him to intercede for Regent Arran to release Cardinal Beaton from imprisonment, alleging the Cardinal's political expertise could be employed to mutual benefit.
Henry VIII wanted English servants in Mary's household, and Sadler recommended "Lady Edongcomb" for this role, his friend the widow of Peter Edgecumbe of Cotehele.


On 10 August 1543 Sadler wrote to Henry VIII describing another visit to Mary of Guise and the infant Queen, this time at Stirling Castle;
"(Mary of Guise) is very glad that she is at Stirling, and much she praised there about the house, and told me, "That her daughter did grow apace; and soon," she said, "she would be a woman, if she took of her mother;" who indeed, is of the largest stature of women.
And therefore she caused also the child to be brought to me, to the intent I might see her, assuring your majesty, that she is a right fair and goodly child, as any that I have seen for her age."

By November Sadler, fearing for his safety as the mood in Edinburgh turned against England, moved to Tantallon Castle, which belonged to the Earl of Angus.
Regent Arran sent the Rothesay Herald to Tantallon, ordering him to return Sadler to England, having "seen daily his great practices made to seduce and corrupt true faithful subjects of this realm to the opinion of England."
The Earl's kinsmen conveyed him to Berwick upon Tweed on 11 December 1543.
All of his work in solidifying Anglo-Scottish relations came to nothing, and war followed after the Scottish rejection of Treaty of Greenwich in December 1543.

Sadler was replaced by William Paget as Secretary of State in April 1543, owing to his frequent absences on diplomatic missions, but was appointed Master of the Great Wardrobe.
He was treasurer for the war against Scotland with the Earl of Hertford during his punitive expedition to Edinburgh in May 1544.
Sadler accompanied Hertford into Scotland, in the same role in September 1545.
 He accompanied Lord Hertford again, this time at the Battle of Pinkie in the post of High Treasurer of the Army.
 On 10 September 1547, in recognition of his services during the fighting, Sadler was made a knight banneret.

Sadlier was present when Stephen Gardiner, Bishop of Winchester, was arrested, and he also accompanied the force that put down Robert Kett's Norfolk Rebellion.
When Henry VIII was preparing his will on Boxing Day 1546, he had already appointed Sadler onto the Council of Regency that was to rule England during Edward VI's minority and left him £200 in his will.

In 1550 Sadler sold his mansion at Hackney.
He was one of the signatories of Edward VI's will in 1553, proving one of the radicals in a Protestant government.
He signed the device set
Sadler was sent into Scotland to several times. In 1540 he tried to embarrass and undermine the authority of Cardinal Beaton, an ally of France, with letters captured from his messenger Alexander Crichton of Brunstane whose ship had been forced by a storm to put into England. However, James V of Scotland refused to accept that the letters were compromising, and argued in favour of the Cardinal that he had a separate spiritual authority in Scotland apart from the King's own temporal powers. Later, when the Cardinal was present, James and Sadler compared the captured letters with Beaton's copies, and found a discrepancy. James V said he was thankful to Sadler and his uncle Henry VIII but still would not find fault in the Cardinal's actions.
Following the Battle of Solway Moss, Sadler was sent to Scotland again, in March 1543, to arrange a marriage between the infant Mary, Queen of Scots, and Edward, Prince of Wales. He was a successful negotiator for the Treaty of Greenwich, although the marriage was not concluded. On 22 March 1543 he rode from Edinburgh to Linlithgow Palace to see the queen for the first time. Mary of Guise showed him the queen out of her swaddling and Sadler wrote that the infant was "as goodly a child I have seen, and like to live". Mary reminded him that in turn Regent Arran wanted his son James Hamilton to marry Princess Elizabeth. Mary tried to work on him to intercede for Regent Arran to release Cardinal Beaton from imprisonment, alleging the Cardinal's political expertise could be employed to mutual benefit. Henry VIII wanted English servants in Mary's household, and Sadler recommended "Lady Edongcomb" for this role, his friend the widow of Peter Edgecumbe of Cotehele.

On 10 August 1543 Sadler wrote to Henry VIII describing another visit to Mary of Guise and the infant Queen, this time at Stirling Castle;
"(Mary of Guise) is very glad that she is at Stirling, and much she praised there about the house, and told me, "That her daughter did grow apace; and soon," she said, "she would be a woman, if she took of her mother;" who indeed, is of the largest stature of women. And therefore she caused also the child to be brought to me, to the intent I might see her, assuring your majesty, that she is a right fair and goodly child, as any that I have seen for her age."
By November Sadler, fearing for his safety as the mood in Edinburgh turned against England, moved to Tantallon Castle, which belonged to the Earl of Angus. Regent Arran sent the Rothesay Herald to Tantallon, ordering him to return Sadler to England, having "seen daily his great practices made to seduce and corrupt true faithful subjects of this realm to the opinion of England." The Earl's kinsmen conveyed him to Berwick upon Tweed on 11 December 1543. All of his work in solidifying Anglo-Scottish relations came to nothing, and war followed after the Scottish rejection of Treaty of Greenwich in December 1543.
Sadler was replaced by William Paget as Secretary of State in April 1543, owing to his frequent absences on diplomatic missions, but was appointed Master of the Great Wardrobe. He was treasurer for the war against Scotland with the Earl of Hertford during his punitive expedition to Edinburgh in May 1544. Sadler accompanied Hertford into Scotland, in the same role in September 1545.  He accompanied Lord Hertford again, this time at the Battle of Pinkie in the post of High Treasurer of the Army.  On 10 September 1547, in recognition of his services during the fighting, Sadler was made a knight banneret. 
Sadlier was present when Stephen Gardiner, Bishop of Winchester, was arrested, and he also accompanied the force that put down Robert Kett's Norfolk Rebellion. When Henry VIII was preparing his will on Boxing Day 1546, he had already appointed Sadler onto the Council of Regency that was to rule England during Edward VI's minority and left him £200 in his will.
In 1550 Sadler sold his mansion at Hackney. He was one of the signatories of Edward VI's will in 1553, proving one of the radicals in a Protestant government. He signed the device set
Ralph Sadler