Henry again strengthened his authority by introducing effective policies on law and order. As well as disciplining his authority over the country as a whole, it particularly impacted upon the nobles. Acts of Attainder were often used against acts of treason by nobles, and from 1485 to 1495 Henry had attainted 80 people who had committed crimes against the Crown. One such person was Thomas Howard, who lost the title of Duke of Norfolk and his family estates after Bosworth. These acts were sometimes reversed as it was in this case, he was reinstated as Earl of Surrey in 1489 to help put down an uprising in Northumberland. This gave Henry ultimate power over his dangerously powerful nobles, meaning he could use them to his advantage when he needed to, as well as being able to suppress them.
However, Henry VII was also unsuccessful in strengthening his authority as King as he continued to be increasingly paranoid about threats from foreign powers and pretenders. His weak hold on foreign policy in Europe meant that in 1491 France began to aid the imposture of Perkin Warbeck, a young man pretending to be Edward, Earl of Warwick, an heir to the English Throne with a stronger claim than the King himself. This could have caused kingmaker nobles who wanted rid of Henry to support the imposture inside the country and threaten Henry's authority.
This suspicion was confirmed when in 1495, it was discovered that William Stanley had been conspiring against the King and trying to help Warbeck's imposture. This made Henry doubt his noble support further. He clamped down on them in terms of financial gains and law and order such as piling bonds and recognisances on magnates he suspected, such as the Marquis of Dorset who had to give a bond after being suspected in the Simnel imposture.
In the Treaty of Medina Del Campo, Princess Catherine of Aragon was contracted to marry Prince Arthur of England. However, In 1489 foreign policy was on thin ice. England was being let down by big European powers such as Burgundy in the Treaty of Dordecht, when Maximilian agreed to send troops to assist Henry in his fight for Brittany against French expansion. Maximilian's troops did not materialise and Henry was left to tackle the French single handedly, making him look weak to the all powerful Spain, of whom his son was to marry the Spanish King's daughter. This made King Ferdinand wary of whether to loose his valuable daughter to such an insignificant country when she could be married to form greater foreign policy with other European powers. This weakened Henry's authority as he was at mercy of the events in Europe, not controlling them for his own gains.
In conclusion, Henry was overall successful in strengthening his authority as a king during the years 1487 to 1497, but mishaps plagued him along the way which could have easily crumbled his authority such as loss of major noble support. If Henry had eventually lost the marriage alliance between Spain this could have altered his position in Europe negatively and made him a target for usurption and impostures. Despite these threats, he swiftly had tight hold of authority as King of England.