Gifts between siblings

I am interested in any UK tax implications of gifts between siblings in two directions. Specifically, consider the following scenario. Person A, a UK resident, makes a substantial cash gift to their sibling, person B, living overseas. The gift is made in good faith, without any expectations for it to be repaid. 10 years later, person B makes a cash gift back to person A (who is still alive), of a value exceeding the original gift from person A. Again, the gift is made in good faith. I am wondering if this will indeed be seen as two independent gifts by HMRC and be free of UK tax, or whether any (CGT-like or other) UK tax might arise on the difference between the gift amounts, or on anything else. Thank you!

Hi,
There are no income tax implications on the receipt of a cash gift unless the cash gift generates interest or dividends, these would then potentially be subject to tax.
Further guidance can be found here (Tax on savings interest and Tax on dividends).   
Thank you.