Well, this article you quote is pure bullshit.
First selling older tank is a rumor and ministrer of defense has said it is false since.
Second: the Leclerc is much superior in some respect to other older tanks like M1 even updated (like the fire on the move ability at long range and all terrain speed).
(One of my friend is a superior officer having lead a Leclerc unit)
Third: France will have rougly the same than British in active units if we reduce Leclerc active units

In July 2004, the UK Ministry of Defence announced plans for a reduction of seven Challenger 2 armoured squadrons (about 100 tanks) by March 2007 and the change of role of one Challenger 2 regiment to an armoured reconnaissance regiment.
www.army-technology.com . . .

Check your information first!