tax implications for moving $ to the UK and back again

I'm saving up for a deposit so I can buy a flat in the next year or so. I was told by another expat that the UK will let you bring in unlimited funds into the UK tax-free, so long as you can prove those funds were earned AND already taxed in your home (not UK) country. If that is true, I could save myself some time and effort by bringing over some of my US savings.

So, first question is: is that true?

Second question is: what if I (for whatever reason change my mind, don't need the money afterall, etc.) want to move those funds BACK to the US at a later date? Will I get taxed on that (in either direction)?

What I'm getting at is whether the tax implications of moving it over (in either direction) outweigh the benefits?

Any thoughts/insight would be greatly appreciated.

Best,
Elise

http://www.hmrc.gov.uk/customs/arriving/declaring-cash.htm
and
http://www.hmrc.gov.uk/customs/arriving/moving.htm

Bringing cash into the UK
There is no tax or duty on cash brought into the UK from outside the EU but you are required to declare cash of 10,000 euros or more (or equivalent).

(from the latter link)

I can't speak to the first part of your question, but when we sold our house in the UK and moved to the US we wire transferred the money into my Wachovia account and never had to pay tax on it.

We did transfer it in multiple transfers though so we wouldn't raise that "money laundering" flag amount at the bank.

You should probably read the HMRC guidance on the remittance basis (yes it is 302 pages and is wrong on the law at some points but it is relevant).
http://www.hmrc.gov.uk/cnr/rdrm-remittances.pdf


It can be found here as well:
http://www.hmrc.gov.uk/cnr/res-dom-tax-amends.htm

the HMRC guidelines are wrong on the law? Superb  Seriously, what are we paying these people for!