Last Saturday night I listened to a couple of Celtic supporters angrily ranting about Neil Lennon following the club’s 1-0 defeat at home to Inverness Caledonian Thistle.

In both cases the gist of the message was this: “If Neil can’t motivate this team, then we’ll find someone else who can...”

I had to stop and check myself at this. Just a week earlier I’d been a part of a different discussion – about how long it might be before Lennon was lured to English football.

First things first: the right of the football fan to vent his spleen at a manager is a given of the game. So long as Mr Angry is not rounding up a lynch-mob to descend on anyone’s house, then the right to angry, even rude, dissent is inviolable.

Lennon’s Celtic are struggling in the SPL. Their statistics – Played 14, Won 7, Drawn 4, Lost 3 – seem abysmal for a club of Celtic’s obvious advantages. It is the club’s worst start to a domestic campaign in 14 years and many Parkhead supporters are affronted by it.

In the aftermath of Saturday’s defeat Lennon even spoke about walking away from Celtic. “If the fans are not happy with me, then I’ll go,” he said.

This was a vivid example of football’s wild, intemperate extremes. Just 15 days earlier Lennon had been lauded across Britain for his team’s 2-1 win over Barcelona in Glasgow. Some commentators even hinted that that result once more put Lennon among the “coming men” of British football coaches.

Well, Terry Butcher’s Caley Thistle threw a spanner into that particular chat. From being lauded, Lennon was suddenly being hounded by some.

The most interesting part of this was Lennon’s immediate reaction to the boos ringing in his ears. It confirmed again that he nurses recurring doubts about where his role lies in football, and the restrictions of life at Celtic.

I remain convinced Lennon was less than enthusiastic about this 2012-13 SPL campaign, given the omission of Rangers. He savours the Old Firm saga and, in the here and now, that is gone.

Lennon respects Scottish football – indeed, he often bats on its behalf – but a fixture card minus the mighty rumpuses with Rangers is not something he salivates over. Among the “Celtic family” Lennon is not alone in this.

Rangers provided the spice. For its rivalry, venom and championship-turning power, the Old Firm fixture is irreplaceable on the Lennon horizon.

Last week, when I heard the Celtic manager diplomatically pronounce something about Aberdeen being the new Rangers, I knew again there was a void left unfilled.

The truth is, Lennon has repeatedly mulled over his Celtic future, and how long he might remain at the club. In one way, for a guy like him, it is a magnificent job. But in another sense, for obvious reasons, Lennon will frequently look to England and the far more enticing atmosphere there.

If Rangers are severely diminished these days, then to a lesser degree, so are Celtic. This is not the electrifying, enticing Celtic Park of the Martin O’Neill era. Indeed, on many Saturday afternoons, it is a drab imitation of it.

Champions League nights are different and, my goodness, doesn’t Lennon know it. But these are few and far between when you are taking on the glum SPL chores - the more so when there is no Rangers looming on the horizon.

Can you blame Lennon for sometimes wanting a change of scene? Barring a brief intermission, he has spent the past 13 years of his life in Glasgow, a city he has come to embrace, warts and all. In football these days that is a lengthy association.

If Lennon takes Celtic into the last 16 of the Champions League – which I believe he will – then a fresh excitement will course through the club. It could happen in little over a week and would be quite a feat by Lennon.

But his mind quite often strays elsewhere in football. When some Celtic fans do vent their spleen in Lennon’s direction, they might only harden his ambition to find a new location.