Charles Tyrwhitt knocks $20 off orders of $20 or more via coupon code "XANU". That's tied with last week's mention as the best dollar-off discount we've seen from Charles Tyrwhitt. Shipping starts at $9.95 and some exclusions apply. Coupon ends January 29.
A best bet is the Charles Tyrwhitt Men's Cotton Socks 3-Pack in Black (pictured) for $25 before the above coupon, $5 after. With $9.95 for shipping, that's $45 off list and the lowest total price we could find. They're available is sizes S to L.