Beware the perils of theatre reviewing.

People sometimes tell me it must be lovely, getting to see all those shows without having to pay for your ticket - and indeed, it is. But from time to time, if you're doing an honest job, you receive a nasty jolt.

I recently had occasion to make an adverse point about a member of the cast of an amateur production. As far as I was concerned, it was simply a factual statement. I wrote it and I thought no more about it - no more, that is, until I learned that the person concerned had been so shocked that he had spoken of giving up his acting hobby altogether.

I don't know whether traumatised is too strong a word to describe him, because I did not see him, but that was the sort of impression I was given - and it meant that I was shocked, too.

It's difficult. As I see it, my role as an interface between amateur groups and the world outside is akin to that of a tightrope-walker. On the one hand, I don't go out of my way to be unkind to people doing their sometimes limited best - but on the other, I have a responsibility to indicate to prospective patrons what they are going to get for their money.

There are ways of doing this. Many years ago, faced with the worst production I have seen and trying my best not to be mistaken for one of the infamous Butchers of Broadway, I did my best to veil my message. I praised the lighting, the scenery and the costumes and I returned home, confident that the Diplomatic Corps would have welcomed me in, no questions asked.

I need not have bothered. My message - as it had to, of course - had clearly got through. My review duly appeared beneath a headline that indicated I hadn't fooled anybody.

"Nice set, Shame about the show."

The point, at least as far as I am concerned, is that criticism is intended to be constructive - to mend a fault, to try to ensure that next time around a lesson will have been noted and things will have improved.

Nobody forces anybody on to the stage, and he who ventures there should not expect plaudits all the way. A certain amount of thickish skin is required.

Certainly, no critic who administers whatever is the opposite of plaundits should be left with the impression that he is ruining lives - be it never so briefly - or prompting his fellow men to think about jumping off bridges.

Meanwhile, I have nothing but praise for Birmingham's Crescent Theatre, now in the throes of its bravura production of Nicholas Nickleby in two three-hour helpings. The first part is by far the lighter and finishes with a romp through Romeo and Juliet. The second is much darker but still accomplished with a fine flourish and a nonstop fluency.

Alas, the patrons for Part 1 on Thursday and Part 2 on Friday were sparsely scattered, although the theatre was living in hope that it had hit break-even. Not that the Crescent works on a profit-per-production basis. Its aim is to have something positive to show for all its efforts over a complete season.

Nevertheless, Nicholas Nickleby has sold very well and it has to be said that Birmingham seems to be largely overlooking the chance to see a superb theatrical exercise. The city has until Saturday - when both parts will be performed - to catch up with what it's missing.

A spot of enterprise on the part of Crossed Keys Musical Theatre Company member Peter Harris has enabled the company to capture the autographs of The Shadows - to display them during next week's production of Summer Holiday, the show of the 1963 film that brought Cliff Richard to the world's attention.

Peter works part-time at the NIA as a steward. He was there on Saturday and realised that The Shadows were to be there 24 hours later, for their last appearance on what is supposed to be their final tour.

He was not going to be there, but he asked a colleague to try to obtain the group's autographs for him.

The mission was successfully accomplished, with the result that the prized pen-work will be on show in the foyer of the Old Rep next week.

Crossed Kays chairman Ron Dixon's only regret is that the show's programmes were not printed in time for one of them to be immortalised on Sunday. The big Brum musical Wallop Mrs Cox returns to its birthplace at the Crescent Theatre next week, in the hands of Northfield Musical Theatre Company - supported by Barry's bells!

The show, written by Euan Rose and Laurie Hornsby, was first performed at the Crescent in 2000, then had two professional productions at Birmingham Rep in 2003 and was presented for the first time outside the city by Solihull operatic society last month.

Laurie's mother, the late Dolly Hornsby, was a member of the Northfield group in the 1970s.

Barry Lankester, former BBC man in the Midlands, has lent a 10-minute recording of the sounds of the Bull Ring to introduce the show, which follows the story of an imaginary family of Bull Ring traders from the early years of the last century to the huge redevelopment.

It includes the bells of St Martin's Church and many of the traders' cries. Society chairman Neil Davies said that producer Peter Walker will use it to lead straight into the show.

The biggest challenge for the company faces Sarah Guest and Chris Evans, playing Emily Cox and her brother-in-law Ernie. They have to get from their early twenties to their nineties.

The production opens on Tuesday.