Buying a Buy to Let myself or gifting the purchase cost to my son for him to manage it

FaceHead

If you gift your son the money and he buys a property with the intention to let it out, he won't receive the first time buyer stamp duty rate. To be eligible you have to intend to live in the property. As others have said he'd then not be eligible for the relief in future, but that seems less relevant. 

However if you buy the buy to let you'd have to pay the additional 3%, so it is still better for the family to buy in your son's name. 

If you later need care, such a large gift could be seen by a local authority as intentional deprivation of assets, and you may become ineligible for support with care home fees.  In order to make such a gift you need to be sure that you don't need the money. If you need the money later, loan it, but this my get in the way of your son getting a mortgage on top of the loaned money. 

oldbikebloke

it is excellent that you are approaching this from a business & financial appraisal perspective, but you seem "obsessed" about currency deflation, in that case buy gold bullion then, as that is the traditional "go to" in periods of currency uncertainty and that certainly is a "tangible asset"

SDLT
in case it has not yet been corrected, if son buys in his own name he will NOT get first time buyers relief as a condition for that is it must be his intention to occupy it as his main home, patently impossible since it will be a BTL.
Son will therefore pay standard rate SDLT - he will however be exempt from higher rate on the purchase of the BTL as that will be the only property he owns.
The implication that he will face higher rate if/when he buys another property to use as his own home has already been mentioned 

theartfullodger

Gift son the £££ if he's any sense he'll buy a place for him to live or spend ££££ on some fun - car, boat, mistress, toy-boy (or both) etc etc etc.

After you gift £££ you have no control over what happens with the money

Artful: 3 sons, all property owners