Although there are sometimes the odd gap in a set of law reports (normally because a volume was borrowed and not returned) the usual problem is that the beginning or end of the series is missing.
The cause here is somebody waiting to subscribe before the series is established or somebody not renewing their subscription and letting the books they own sit on the shelf as time passes and more volumes are published.

Filling in gaps at the end can often be straightforward. You may find what you need on this site or elsewhere (see below). It is common for law students to take a series (say the Official Reports) for a few years and then when they decide their future is not in the law to sell off the 5 years or so they have collected.

Finding the early parts of a series is much more difficult. With modern reports you may be lucky and find the unbound parts that somebody has collected but with something like the Official Reports it is much more difficult. Be prepared to buy more than you want from a vendor (e.g. they have 20 years spanning a gap you have of 15 years) and sell the balance you do not need.

The golden rule is – take your time.

Sources:

  1. This website.
  2. Wildy’s of Lincoln’s Inn Archway, Carey Street, London WC2A 2JD are the pre-eminent source for second hand works in the UK. I have always found them helpful and their knowledge of law books is second to none.
  3. The Incorporated Council f Law Reporting has a supply of parts and volumes for the Official Reports and the WLR – not cheap but at least they are available. Unfortunately their web site is not easy to navigate nowadays – best to give them a call.
  4. Ebay – obviously.
  5. Other sites such as bookfinder.com