City of London Building Society v Flegg [1987] UKHL 6 is an English land law case decided in the House of Lords on the relationship between potential overriding interests and the concept of overreaching.

[n 2] Their daughter and her husband, Mrs and Mr Maxwell-Brown also chose the house; they also put in the balance to buy (£16,000) by taking out a mortgage loan (with an earlier lender) which they would pay back.

The law means Mr and Mrs Flegg had an equitable property right, stake or share from their contributions which the Maxwell-Browns held on trust for them.

Dillon LJ held that, reversing the decision of the High Court, the Fleggs' interest in their home was not overreached through the building society's contract with the children.

But, again, this argument is inconsistent with the scheme of the Land Registration Act 1925 as explained in the passages in Lord Wilberforce's speech in Boland's case which I have quoted above.

The Judicial Committee of the House of Lords held that the building society's charge took priority, and could use the overreaching defence against the Fleggs’ pre-existing trust right.

Although under the Land Registration Act 1925 section 70, people with actual occupation may have an overriding interest that would take priority over a third party, like the building society, this does not happen if the purchase money is paid to two or more trustees or a trust corporation.