on the history of the Earldom of Huntingdon:
After Earl Simon's [Matilda's 1st husband] death, his Widow married David I of Scotland, who consequently became Earl of Huntingdon too, keeping the Earldom even after he succeeded his brother as King of Scots. He sided with the Empress Maud against Stephen I but came to terms with the latter and made the Earldom over to his son Henry. Henry swore fealty to Stephen but subsequently fought against him under the Scottish banner, which may account for Simon de St Liz's son, another Simon, being recognized as Earl of Huntingdon before Henry's death in 1152. [Burke's Peerage]
---------------------------------------------------
Henry, son of the said David, King of Scotland, on condition of swearing allegiance to Stephen, had the Earldom and honour of Huntingdon, with the borough of Doncaster and Carlisle as an augmentation thereto. He was in such high estimation with King Stephen that, upon that monarch's solemn celebration of the feast of Easter, he placed the Earl of Huntingdon on his right hand, which gave such displeasure to the nobility then present that William Corbois, or Corbel, Archbishop of Canterbury, Ranulph, Earl of Chester, and several others withdrew from court. He m. Ada, sister of William, Earl of Warrenne and Surrey, and had issue, Malcolm and William, successively Kings of Scotland, David, Ada, m. to Floris, Earl of Holland, and Margaret, m. to Conan le Petit, Earl of Brittany. The earl d. in 1153, a little before his father, and, upon his decease, Simon de St. Liz, Earl of Northampton, was restored to the Earldom of Huntingdon. [Sir Bernard Burke, Dormant, Abeyant, Forfeited, and Extinct Peerages, Burke's Peerage, Ltd., London, 1883, p. 468, St. Liz, Earls of Huntingdon]