The Loudon Co. Paxons were most certainly from Bucks Co., however, I have no information on your line other than the following from which you may find a start:
1 Henry Paxon
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Death: 9 May 1756, Age 73 Yrs. Buckingham MM, Bucks Co. PA
Father: James Paxon (1640-1722)
Mother: Jane Gurden

Paxon Family
Jane Paxon, wife of James Paxon, departed this life the 7th day of the second month 1710
James Paxon departed this life the 29 of the 7th mo. 1722
1. William Paxon son of Henry and Ann Paxon was born the 31 of the 11 th mo. 1707
2. Elizabeth Paxon was born the 11 of the 4th mo. 1709
3. Mary Paxon was born the 25 of the 2nd mo. 1711
4. Sarah Paxon was born the 25 of the 11th mo 1712
5. Jane Paxon was born the 14 of th 11th mo. 1714
6. Margery Paxon was born the 24 th of the 9th mo 1716
7. Ann Paxon was born the 8 of 11th mo 1718
8. Recbecca Paxon was b. 5th of 9th mo 1720
9.Henry Paxonn was b. 28 of 6th mo 1722
10.James Paxon was b. 8th of 6th mo 1724
11. Thomas Paxon was b. 17th of 4th mo 1726
12. Martha Paxon was b. 4th of the 12th mo 1728

Ann Paxon w/o Henry Paxon departed this life the 10th of 12th mo. aged 40 yrs., 1728

William Paxon s/o Henry departed this life 7th day 5th mo, age 23 y 5m and 7d, 1731
James Paxon s.o Henry departed this life the 1st d 9mo age 19y 2 mo 23 d.,1743
Henry Paxon father of the above named ch departed this life the 5th d of the 9th mo age 73 yes and 1 mo and 15 days, 1756

Spouse: Ann Plumly
Birth: 15 Jan 1687, Middleton, Bucks Co., PA
Death: 10 Feb 1728, Age 40 Yrs. Buckingham MM, Bucks Co. PA
Father: William Plumly (1666-<1699)
Marr: 5 Jan 1706/1707, Middleton, Bucks Co. PA
Children...
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1. F Child: Elizabeth Paxon - 2275
Birth: 11 Apr 1708/1709
Death: 4 Dec 1786 Place: Bucks Co. PA; 78 Yrs
Spouse: Thomas Hartley - 2274
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2. M Child: Henry Paxon - 1292
Birth: 28 Jun 1722 Place: Buckingham MM, Bucks Co. PA
Death: 8 Feb 1799
Spouse: Elizabeth Lupton - 1293
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3. M Child: William Paxon - 2431
Birth: 31 Jan 1707 Place: Buckingham MM, Bucks Co. PA
Death: 5 Jul 1731
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4. F Child: Mary Paxon - 2432
Birth: 24 Feb 1711 Place: Buckingham MM, Bucks Co. PA
Death: 31 Aug 1719
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5. F Child: Sarah Paxon - 2433
Birth: 25 Nov 1712 Place: Buckingham MM, Bucks Co. PA
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6. F Child: Jane Paxon - 2434
Birth: 14 Nov 1714 Place: Buckingham MM, Bucks Co. PA
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7. F Child: Margery Paxon - 2435
Birth: 24 Sep 1716 Place: Buckingham MM, Bucks Co. PA
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8. F Child: Ann Paxon - 2436
Birth: 11 Aug 1718 Place: Buckingham MM, Bucks Co. PA
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9. F Child: Rebecca Paxon - 2437
Birth: 9 May 1720 Place: Buckingham MM, Bucks Co. PA
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10. M Child: James Paxon - 2438
Birth: 6 Aug 1724 Place: Buckingham MM, Bucks Co. PA
Death: 9 Jan 1743
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11. M Child: Thomas Paxon - 2439
Birth: 17 Apr 1726 Place: Buckingham MM, Bucks Co. PA
Death: 13 Jan 1764
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12. F Child: Martha Paxon - 2440
Birth: 13 Apr 1728 Place: Buckingham MM, Bucks Co. PA