The information below is borrowed from GenUKI Wales Web site:

"The Tithe Commutation Act, 1836, provided for the valuation of lands subject to payment of tithe in order to substitute a money rent for the existing system of payment in kind.  In the period 1838 to 1854 an original large-scale tithe map with two copies was prepared for each parish.  The original maps were deposited with the Tithe Commissioners, and are now in the Public Record Office.  One copy was deposited with the diocesan registrar, and these are now (for parishes in Welsh dioceses) in the National Library of Wales. The other copy was deposited with the incumbent and church wardens of the parish concerned.

"The maps are accompanied by a written apportionment, which usually gives the following information for each numbered parcel of land on the map: name of landowner; name of occupier; parcel number on the map; name and description of the property; state of cultivation; quantity in acres, roods and perches; and amount of rent-charge payable in lieu of tithes.

"Most County Record Offices in Wales have some of the parish copies mentioned above but they also have copies of tithe maps (mostly photocopies) and apportionments (mostly on microfilm) for parishes in their own county obtained from the National Library.

"Further information: J. West, Village Records, (Macmillan 1962)."

The Tithe Apportionments and Map for the village of St. Bride's-super-Ely has been transcribed and included on this site.  They are presented as follows:

• Introduction by Commissioner John Johnes
• Chart of Tithes Payable, showing land ownership and occupancy
• Summary
• Map of Parish, showing land occupancy.  Note:  Each map is 50KB-100KB in size so may be slow to load.