Celtic have been very active in the transfer market over the last few days, completing back-to-back big-money signings.

Haissem Hassan was brought in from Real Oviedo after weeks of speculation. That was followed by the arrival of Mika Baur the very next day.

Naturally, the mood has been lifted around Parkhead. After weeks of facing heavy criticism from the supporters, the board is actually getting some plaudits.

But now, it looks like Baur's arrival might have been preparation for a big-money departure of their own. In fact, a record in English Championship history.

According to Anthony Joseph, Arne Engels has agreed terms on a five-year deal with West Ham United.

The clubs had already agreed a £22 million deal for the Belgian international. Engels is due to undergo a medical in London today.

Of course, this £22 million transfer fee will make Engels the most expensive signing in the history of the Championship.

As for Celtic fans, many of them will question the thinking behind leaving potential Champions League football to play in the Championship.

Then again, Engels might be viewing this as a long-term play. Ryan Christie made a similar move to the Championship in 2021, albeit for a much smaller fee, and ended up becoming a stalwart in Bournemouth's team in the Premier League, when they went up and established themselves in the English top flight.

Yes, West Ham United are in the Championship but they are expected to go straight back to the Premier League. If or when they do, the Hammers have the resources to establish themselves in the top flight once again.

At the end of the day, we do not know the other opportunities that were available to Engels, if any.

He spent a couple of seasons at the club, was instrumental in the title run-in last season and is now set to move for double of what Celtic had paid to sign him just two summers back.

So, there is very little room for complaints. We can only wish him the best of luck and hope that he goes on to have a great career ahead.

It remains to be seen whether Baur has been signed as the direction one-for-one Engels replacement or whether Celtic will look to make another addition in the middle of the park this summer. Let us not forget that Paulo Bernardo has also left, while Reo Hatate is widely expected to do the same very soon.