I am looking for a very recent (2006?) House of Lords decision about a
"time is of the essence" case. The facts are a real estate transaction
was being
concluded by courier, who arrived 10 minutes past the time specified
for closing in the contract. The monies involved were in the millions.
The decision held the contract was void for breach of a fundamental
term--"time is of the essence". In other words, that may have been the
costliest 10 minutes   in real estate ever.

Although there is no case that corresponds to a UK House of Lords
judegement for 2006 (http://www.publications.parliament.uk/pa/ld/ldjudgmt.htm),
there is a case that fits the details of your query, namely Union
Eagle Ltd v. Golden Achievement Ltd (1997) 
(http://www.ucc.ie/law/restitution/archive/hkcases/union3.htm and
http://www.austlii.edu.au/au/journals/UNSWLJ/2001/10.html), which
corresponds to a 10 min late real estate contract in the millions.