Transmission lines designed and built by Peter Elvins in Dalston. Possibly his TL48P in which case they have 2 8" Seas bass drivers and a Seas tweeter. 8 ohm impedance
Other speakers manufactured by Elvins were also TLs, two-way, ported, two pairs of gold-plated binding posts, polypropylene bass/midrange, and soft dome tweeter.
Depending on specific model, response is 30-38Hz thru 20kHz, sensitivity between 86 and 90db.
Do you know how tall they are? Elvins manufactured TLs between 800 and 1200mm high. If they are heavy, it's probably because the bottom compartment has 25kg of lead shot in it.
mole0937 sold a pair on here just over a year ago:
http://www.hifiwigwam.com/showthread.php?66297