Will uk banks accept cashiers checks in us dollars?

Yes but they do make a charge.

I expect that UK banks are probably well aware that there is an
epidemic of counterfeited cashier's checks. This might result in a
delay while the authenticity of the check is verified.

Have just checked with the last $ check that I paid into my UK bank.
There was no charge.

It wasn't a Cashier's check, just an ordinary one.

The slip says that it was accepted for 'Negotiation' and that 'All
Negotiations are with recourse to the Customer'.

I wasn't aware of 'the spate of counterfeited cahier's checks' advised
by pinkfreud.

So, BEWARE!

If an ebay purchaser (for example) is offering you one such ... You've
got to wonder why ...

There are now so many easier (and more secure) ways of making
International Payments, PayPal, for example.

Clearly, the term 'Cashier's Check' suggests great security which may be spurious.

A bonafide cashier's check is issued by a bank, eliminating the
greater risk that company or individual issuing a check (cheque) could
represent.  For the bank, clearing either kind of check is no
different and there should certainly be no additional charge for
clearing a cashier's check.

If PB's bank is like my German one, it may credit the US check
immediately, but not consider the amount as available funds until 6
weeks later, allowing time to reverse the credit if the check is
returned for any reason.