Spirent, the Crawley-based electrical and electronic components manufacturer which used to be called Bowthorpe, has come a long way.

Things have improved a lot in the three years and a bit since Nicholas Brookes took over as chief executive.

Then it was a bit of a ragbag of a group covering 100 companies with 26 different product areas, many concentrating on local markets.

The business had been growing in a desultory fashion by about five to ten per cent a year.

Brookes felt it needed more focus and rationalisation and slimmed it down to five core divisions.

He felt it should go global, particularly increasing its presence in the U.S.

He shed non-core operations like thermal testing and aerospace systems and moved into high technology.

Most significant of all, he effectively turned it into a leading supplier of network-testing technology for internet service providers.

Now the company is about to join the FTSE 100 list of the UK's largest companies and is talking about a quote on Nasdaq, the U.S. technology stock market, within the next 12 months.

Excluding goodwill amortisation on the acquisition of two companies, pre-tax profits for the six months to June were 31 per cent higher at £59 million.

After exceptional costs and a £11 million loss on selling non-core businesses, pre-tax profits slipped from £38.5 million to £32.7 million. Earnings per share were 2.48p (4.22p) but the interim dividend was raised to 1.44p (1.33p).

But the key point was the main division, Spirent Communications, which makes the telecoms-testing equipment, grew organically by 80 per cent in the period under review.

Its clients include BT, Ciena and Lucent of the U.S., Canada's Nortel and Ericsson of Sweden.

So the company has not just grown by acquisition.

It nevertheless continues to expand by buying new companies, essentially one suspects to keep up with the breathtaking speed of new development and products in the sector.

Spirent said it has conditionally agreed to buy U.S. group Zarak Systems in a move to further bolster its position in the testing field.

Zarak is a leading designer and manufacturer of communications test equipment focused on the generation and switching of voice traffic.

Mr Brookes said Zarak would reinforce Spirent's technological expertise.

Zarak will be acquired for Spirent shares in a deal valuing it at $403 million (£284 million).

Spirent shares have tripled over the past nine months and it is well and truly in the frame as a good-value internet stock.